Week 1

Week 1

Lecture 1

Biological basis of behaviour

 We must look at behaviour as a biological phenomenon

o Our brain influences our 'mind' (read: state of consciousness) and our body influences our brain, and the environment influences our body

o Hence the environment influences our mind

 There are several levels of analysis for the human brain, from macro to micro:

o Group behaviours o Individual behaviours o Cognitive processes o Neural events o Molecular events o Subatomic events

 Many lawful patterns can only be understood at one level of analysis - we call this the functional level

 Knowledge at one level can help ground our understanding at others

o e.g. if we understand the physical process behind emotion, we can manipulate this while examining brain responses

o Better functional understanding means we can better identify the activity responsible for the different processing stages

 Therefore, neuroscience is not a replacement for psychology, as it helps build an integrated understanding

Lecture 2

Psychobiology 1 - The Nervous System

Anatomy of a neuron

 Neurons or nerve cells transmit information

o Humans have about 86 billion, or about 160,000km worth

o

 The parts of a neuron are:

o Dendrites: branch-like structures that receive information from other neurons o Soma or cell body: protects the nucleus and cell contents

 Phospholipid bilayer: maintains the negative charge within the cell o Nucleus: the engine room, contains the genetic material and produces

neurotransmitters

o Axon hillock: the transmission 'gatekeeper'

 Graded potentials are aggregated to determine if an action potential will be fired o Axon: a long nerve fiber which conducts electrical signals from the cell body

 Myelin sheath: coating that insulates the axon, and allows for faster signalling (also produced by Schwann cells)

 Multiple Sclerosis (MS) is an auto-immune disease which leads to the failure of cells which create the myelin coating, reducing speed of signal

transmission

 Nodes of Ranvier: sections of bare axon which allow transmission to continue down

 Axon terminals (terminal buttons): where the chemical messages are sent into synapses

 Types of neurons:

o Multipolar neuron:

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o Bipolar neuron:

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o Unipolar neuron:

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 Classification by function:

o Sensory neurons

 Activated by a sensory input, e.g. vision, somatic, auditory

 Tend to be unipolar or bipolar

 Sends afferent signals, i.e. towards the brain o Motor neurons

 Sends efferent signals, i.e. from the brain

 Cell body located in the spinal cord and axon projects to the muscles

 All multipolar neurons o Interneurons

 Neurons that only connect to other neurons, e.g. those in the brain

 Usually multipolar

 Involved in higher order processing, e.g. memory and cognition

 There are lots of types of neurons though:

o

The nervous system

 All of these neurons form the nervous system:

o Central nervous system (CNS) comprises the brain and the spinal cord

o Peripheral nervous system (PNS) comprises all other nerves, e.g. going out to muscles, and sensory receptors. The PNS contains:

 Somatic nervous system (SNS): control of body movements via skeletal muscles (efferent)

 Transmits sensory information from the periphery to the CNS (afferent)

 Autonomic nervous system (ANS): parasympathetic nervous system and sympathetic nervous system



The Peripheral Nervous System

 The somatic nervous system controls reflex actions. Note that this is done in such a way that the signal does not have to travel to the brain:

o

 Controlled movement does involve the brain however:

o Brain receives somatosensory input

o Information is integrated and the motor cortex initiates action o Somatic motor neurons control muscle actions

 The Autonomic nervous system controls two functions through two systems:

o

o The parasympathetic nervous system can be thought of as the bodily functions of a person in a relaxed state, e.g. breathing out, slow heart rate, (relaxed rectum)

o On the other hand, the sympathetic nervous system is the 'ready for action' part of the normal bodily functions, i.e. deals with stress responses, such as fast heartbeats, dilated pupils, (contracted rectum)

Lecture 2

Introduction to Neuroanatomy

Brain terminology

 Orientation

o Rostral or anterior: front of the brain o Caudal or posterior: back of the brain o Dorsal or superior: top of the brain o Ventral or inferior: bottom of the brain

 Sectioning

o Sagittal: a cross section from front to back (for vertical cross sections) o Coronal: a cross section from side to side

o Axial or horizontal: a cross section from front to back (but through the side, i.e. the cross sections are horizontal)

 Topography

o

o Gyrus: a ridge on the cerebral cortex o Sulcus: a depression in the cerebral cortex o Fissure: a deeper groove in the cerebral cortex

Brain evolution and development

 The brain has evolved over hundreds and millions of years

 All animals tend to have similar hindbrains and midbrains, but the key points of difference are in the forebrain

 Hindbrain: control of vital functions

 Midbrain: a relay station, posture and movement, sleep, etc.

 Forebrain: everything else, e.g. memory, cognitive processes, etc.

 Hindbrain consists of:

o

o Medulla: autonomic centre for heart rate and blood pressure

 Cranial nerve input

o Pons: relay signals between periphery and brain, respiration, cranial nerve integration o Cerebellum: fine motor control

 Damage to the cerebellum causes cerebellar ataxia

 Circled bit below:

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 Midbrain consists of:

o

o Tectum:

 Superior colliculus: visual processing and control of eye movements

 Inferior colliculus: auditory processing

o Tegmentum: unconscious processes and movement

 Forebrain consists of:

o Hypothalamus: adjacent to the pituitary gland. Controls much of the endocrine system, sex hormones, etc.

 Important for homeostasis, e.g. body temperature, blood pressure, fat content, etc.

o Thalamus: filters and relays sensory signals to the cerebral cortex o Amygdala: involved in emotion and fear responses

 Also important with aggression (mice being made to kill crickets by activating the amygdala)

o Hippocampus: formation and storage of new memories

 Story of HM, hippocampal removal --> anterograde amnesia (can't form new memories) and partial retrograde amnesia

 Water maze - mouse can't find its way or learn from previous training with hippocampal lesions (i.e. hippocampi have been removed)

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o Cerebral cortex or cerebrum:

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 The bit in between the frontal lobe and the parietal lobe is the central sulcus

 In between the front lobe and the temporal lobe is the lateral fissure

 The frontal lobes are used for:

 Executive function

 Abstract thinking

 Impulse control and social skills

 Motor cortex

 Phineas Gage: rod through the frontal lobe, became a changed person, poor social skills, hypersexuality, etc. but lived for 12 more years

 The frontal lobotomy: icepick straight through the nose and sever the connections

 Sometimes caused passivity, popularised in the US used on 40,000 patients o Motor cortex for motor skills

o Parietal lobe: involved in somatosensory interpretation

o Temporal lobe: primary auditory cortex and primary olfactory cortex o Occipital lobe: visual processing

o Each sense also has a primary cortex, and there are also association areas

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o Corpus callosum: white matter tract (white because of about 250 million myelinated axons) that connect the two hemispheres

 Split-brain patients who are found to have two virtually independent brains

 e.g. flash a word on the left (so only the right hemisphere can see it)

 the patient can't say what he saw (verbal processing is left hemisphere) but he can draw it