Brain Structure and Function

Overview Lobes of the brain (Forebrain) Lobes of the brain (Forebrain) Midbrain/Hindbrain Midbrain/Hindbrain Protection and Blood supply Protection and Blood supply Structure and Function of a neuron Structure and Function of a neuron Synaptic Transmission Synaptic Transmission Neurotransmitters Neurotransmitters

The brain Most complex organ of the body Most complex organ of the body Only weighs 1,300 grams Only weighs 1,300 grams Contains billions of neural networks that interact to create human behaviour Contains billions of neural networks that interact to create human behaviour

Forebrain Cerebrum and Cerebral cortex Cerebrum and Cerebral cortex Left and Right Hemispheres Left and Right Hemispheres Left hemisphere for most people is the dominant hemisphere- responsible for production of language, mathematical ability, problem solving, logic Left hemisphere for most people is the dominant hemisphere- responsible for production of language, mathematical ability, problem solving, logic Right hemisphere thought to be responsible for creativity and spatial ability Right hemisphere thought to be responsible for creativity and spatial ability

(Barlow and Durand, 2005)

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

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(Barlow and Durand, 2005)

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

Temporal Lobes Located at each side of the brain Located at each side of the brain Involved in receiving and processing auditory information, higher order visual information, complex aspects of memory and language Involved in receiving and processing auditory information, higher order visual information, complex aspects of memory and language Wernicke’s Area- Comprehension of speech Wernicke’s Area- Comprehension of speech

(Barlow and Durand, 2005)

Occipital lobes Rearmost portion of the brain Rearmost portion of the brain Visual processing area Visual processing area Corpus Callosum- Fibre bundle in the brain that connects the two hemispheres together. Corpus Callosum- Fibre bundle in the brain that connects the two hemispheres together.

Diencephalon Thalamus- filters sensory information, controls mood states and body movement associated with emotive states Thalamus- filters sensory information, controls mood states and body movement associated with emotive states Hypothalamus- ‘Central control’ for pituitary gland. Regulates autonomic, emotional, endocrine and somatic function. Has a direct involvement in stress and mood states. Hypothalamus- ‘Central control’ for pituitary gland. Regulates autonomic, emotional, endocrine and somatic function. Has a direct involvement in stress and mood states. ( ule_anatomy/unit5_3_nerve_org1_c ns.html)

Hindbrain Cerebellum- regulates equilibrium, muscle tone, postural control, fine movement and coordination of voluntary muscle movement. Cerebellum- regulates equilibrium, muscle tone, postural control, fine movement and coordination of voluntary muscle movement. Pons- Relay station between cerebrum and cerebellum Pons- Relay station between cerebrum and cerebellum

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Medulla oblongata- Conscious control of skeletal muscles, balance, co-ordination regulating sound impulses in the inner ear, regulation of automatic responses such as heart rate, swallowing, vomiting, coughing and sneezing Medulla oblongata- Conscious control of skeletal muscles, balance, co-ordination regulating sound impulses in the inner ear, regulation of automatic responses such as heart rate, swallowing, vomiting, coughing and sneezing Reticular Formation- Important in arousal and maintaining consciousness, alertness attention and Reticular Activating System which controls all cyclic functions i.e. respiration, circadian rhythm. Reticular Formation- Important in arousal and maintaining consciousness, alertness attention and Reticular Activating System which controls all cyclic functions i.e. respiration, circadian rhythm.

Basal Ganglia- Control of muscle tone, activity, posture, large muscle movements and inhibit unwanted muscle movements. Basal Ganglia- Control of muscle tone, activity, posture, large muscle movements and inhibit unwanted muscle movements. Substatia Nigra- Produces dopamine is connected to the basal ganglia. – EPSE’s Substatia Nigra- Produces dopamine is connected to the basal ganglia. – EPSE’s (Barlow and Durand, 2005)

The Limbic system Amygdala- mediates and controls major affective mood states such as friendship, love, affection, fear, rage and aggression. Amygdala- mediates and controls major affective mood states such as friendship, love, affection, fear, rage and aggression. Hippocampus- Memory, particularly the ability to turn short term memory into long term memory. Alzheimer's disease. Hippocampus- Memory, particularly the ability to turn short term memory into long term memory. Alzheimer's disease. (Barlow and Durand, 2005)

Protection and Blood Supply Meninges- Dura mater and Pia mater Meninges- Dura mater and Pia mater CSF- 2 main functions ; shock absorption and mediation of blood vessels and brain tissue in exchange of nutrients. CSF- 2 main functions ; shock absorption and mediation of blood vessels and brain tissue in exchange of nutrients. Circle of Willis –carotid arteries and baliser arteries. Circle of Willis –carotid arteries and baliser arteries. Blood brain Barrier- Protect the brain from chemicals in the blood. Made up of tightly packed Endothelial cells/capillaries making it difficult to penetrate. Blood brain Barrier- Protect the brain from chemicals in the blood. Made up of tightly packed Endothelial cells/capillaries making it difficult to penetrate. ( ancer.gov/module_an atomy/unit5_3_nerve _org1_cns.html)

Structure of a Neuron ( This image has been released into the public domain by its author, LadyofHats. This applies worldwide.)public domainLadyofHats

Function of a Neuron Resting potential Resting potential - positive/negative charge - voltage gated channels - sodium/potassium pump Action potential Action potential - threshold -depolarisation (This image has been released into the public domain by its author)public domain

Action potential (Rosenweig, Breedlove and Leiman,2005 pg 64 )

Synaptic transmission Calcium ion channels Calcium ion channels Synapse Synapse Lock and key effect Lock and key effect reuptake reuptake (This image has been released into the public domain by its author)public domain

Neurotransmitters - Acetylcholine (ACh) Release through the brain via cholinergic pathways. Plays role in: - cognition (memory) - sleep/wake cycle - parasympathetic nervous system - regulation of heart rate, digestion, production of saliva,bladder function. - smooth muscle contraction ( Boyd, 2002 )

Monoamines Norepinephrine (NE) Norepinephrine (NE) Found mainly in 3 areas of the brain; the locus coeruleous, the pons and reticular formation. Main role; - attention, alertness, arousal -sleep/wake cycle - regulating mood/anxiety (Barlow and Durand,2005)

Dopamine (DA) Dopamine (DA) Almost a million nerve cells in the brain contain dopamine. Role in ; - complex movement -cognition - motor control - emotional responses such as euphoria or pleasure. Newer antipsychotic medication focus on particular dopaminergic pathways in the brain. Lessening EPSE’s. (Barlow and Durand,2005)

Serotonin (5HT) Serotonin (5HT) Believed to be one of the great influences on behaviour. Complex neurotransmitter. Surprisingly only 2% of serotonin is found in CNS. Roles include - Vasoconstriction, gastrointestinal regulation. - Low serotonin associated with aggression, suicide, impulsive eating, anxiety and low mood. - regulates general activity of the CNS, particularly sleep. - Delusions, hallucinations and some of the negative symptoms of schizophrenia. (Barlow and Durand,2005)

Amino Acids Glutamate Glutamate - found in all cells - controls opening of ion channels - blocking glutamate produces psychotic symptoms - Over exposure to glutamate causes cell death GABA( Gamma-aminobutyric acid) GABA( Gamma-aminobutyric acid) - Only found in CNS - Inhibitory neurotransmitter - controls excitatory neurotransmitters - Implicated in anxiety disorders

References Boyd (2002). Psychiatric Nursing, contemporary practice.Lippincott, USA Boyd (2002). Psychiatric Nursing, contemporary practice.Lippincott, USA Rosenweig, Breedlove and Leiman (2002) Biological Psychology: an introduction to cognitive, behavioural and clinical neuroscience 3rd Edition.Sineur Associates, Inc USA. Rosenweig, Breedlove and Leiman (2002) Biological Psychology: an introduction to cognitive, behavioural and clinical neuroscience 3rd Edition.Sineur Associates, Inc USA. Stuart and Laraia (2005) Prinicples and Practice of Psychiatric Nursing. Mosby, USA. Stuart and Laraia (2005) Prinicples and Practice of Psychiatric Nursing. Mosby, USA. Barlow and Durand (2005). Abnormal Psychology, and intergrated approach.Thompson/Wadsworth, Australia. Barlow and Durand (2005). Abnormal Psychology, and intergrated approach.Thompson/Wadsworth, Australia. Leonard BE (1997). Fundamentals in Psychopharmacology. 2nd ed. Chichester: Wiley & Sons. Leonard BE (1997). Fundamentals in Psychopharmacology. 2nd ed. Chichester: Wiley & Sons. Purves DE, Augustine GJ, Fitzpatrick D, et al. (eds). Neuroscience. Sunderland, MA: Sinauer Associates, Inc; Purves DE, Augustine GJ, Fitzpatrick D, et al. (eds). Neuroscience. Sunderland, MA: Sinauer Associates, Inc; Lundbeck Institute, Lundbeck Institute, Blakemore & Frith (2005). The Learning Brain. Blackwell Publishing Blakemore & Frith (2005). The Learning Brain. Blackwell Publishing Begley (2005). The blood brain Barrier. Gauchers News May 2005c Begley (2005). The blood brain Barrier. Gauchers News May 2005c