Full lecture notes for Lancaster University Psychology module PSYC112 An Introduction to Neuroscience. Includes definitions, diagrams, research findings and citations.
PSYC112 Michaelmas Term – An Introduction to Neuroscience
Lecture 1 – What is Neuroscience
- All psychological phenomena are a result of the physiology of the nervous system.
- Neurons - cells that receive and transmit electrochemical signals.
- There are 80 billion neurons in the brain. Each is connected to 1000 or more other neurons.
- Action potential – the electrical signal passed down from individual neurons.
- Neurotransmitters – information transmitted between neurons in the form of chemical signals.
- Subdisciplines of neuroscience: Biopsychology: the biology of behaviour / Neuroanatomy: structure of
the nervous system / Neurochemistry: chemical bases of neural activity / Neuroendocrinology:
interactions between the nervous system and endocrine system / Neuropathology: nervous system
disorders / Neuropharmacology: effects of drugs on neural activity / Neurophysiology: functions and
activities of the nervous system / Neuropsychology: studies psychological effects of brain damage using
quasi-experiments and case studies / Psychophysiology: relation between physiological activity and
psychological processes in human subjects using non-invasive procedures such as EEG / Cognitive
Neuroscience: study of neural basis of cognition using fMRI / Physiological Psychology: study of the neural
mechanism of behaviour. Uses direct manipulations of the brain in controlled conditions eg. surgery
(usually on lab animals but also possible on humans)
- The Connectome – comprehensive map of neural connections in the brain; a ‘wiring diagram’. It is not
completed.
- Over the last 2-3 million years, our brain size has almost tripled (450 -> 1300g). Most of the increase has
been in the amount of the cerebral cortex.
- The brain takes in 20% of our energy’s needs.
- Machiavellian Hypothesis – we evolved big brains in order to manipulate each other in social situations
(plotting against other individuals to gain status). Big brains may have been needed for the sophisticated
use of language and for interpreting the intentions of others.
- Evidence against Machiavellian Hypothesis - baboons and chimpanzees show Machiavellian Intelligence
but there is no evolutionary pressure on them to develop large brains to compete with each other.
- Seduction – Miller suggested that the brain evolved to attract members of the opposite sex. Brain size is
hypothesised to be a sexually selected characteristic. Brain size itself may offer little to no survival
advantage but the skills that go along with it make us attractive to the opposite sex.
- Advantages of studying human subjects: can follow instructions / can report subjective experiences /
cheaper to work with / have a human brain
- Advantages of studying non-human subjects: fewer ethical restrictions (can perform invasive
experiments) / simpler brains (more likely to reveal brain-behaviour interactions) / can compare with
other species
Lecture 2 – Neuroanatomy
The Nervous System
- Function is to facilitate communication between the different
parts of the body and to process information
- Neurons provide high-speed electrical connections between
different cells in the body to analyse info and plan actions
- The brain is a complex way of relating sensations to actions
- Efferent = Autonomic. Nerves that carry info away from the
CNS to the peripheral / Afferent = Somatic. From sensory organs
back to CNS.
Anatomical Directions of the Brain
- Dorsal – upper / superior portion of the brain, but refers to the back when discussing the spinal cord (as
humans stand upright)
- Ventral – lower / inferior portion of the brain, but refers to the back when discussing the spinal cord
, - Caudal – posterior / means ‘towards the tail’ and indicates the direction towards the feet. Directs
towards the back of the brain
- Rostral – anterior / means ‘towards the nose’. Frontal part of the brain. For the spinal cord it indicates the
direction pointing upwards to the head.
- Lateral – towards the side of the brain / further away from the midline
- Medial – closer to the midline of the brain
Planes of sections
- Coronal / Frontal – divides into rostral (frontal) and caudal (back). Sliced similarly
to a loaf of bread
- Horizontal / Axial / Transverse – divides the brain into dorsal / superior (upper)
and inferior / ventral (lower) parts. Sliced similarly to a bagel.
- Sagittal / Lateral– divides the left and right side of the brain.
Protection of the Central Nervous System
CNS is encased in bone and covered by 3 membranes (meninges):
- Dura mater: tough outer membrane
- Arachnoid membrane: web-like
- Pia mater: adheres to CNS surface
- Cerebrospinal Fluid (CSF): Found between arachnoid membrane and pia mater
and also in ventricles. Protects the surface of the brain by acting as a cushion.
Five Major Divisions of the Brain
Forebrain
Telencephalon: involved in regulation of voluntary movement. Interprets sensory
input and mediates complex cognitive processes such as learning, speaking and
problem solving.
- Cerebral cortex: Composed of small unmyelinated neurons – often referred
to as grey matter. Responsible for analysing sensory information and higher
brain functions. 90% of human cerebral cortex is neocortex (new cortex that is
six-layered) Large furrows in a convoluted cortex are called fissures. The
longitudinal fissure is a groove that separates right and left hemisphere. The
corpus callosum is the largest hemisphere-connecting tract. The central fissure
and the lateral fissure divide each hemisphere into the four lobes. (see more at
Four Lobes)
- Basal Ganglia: a group of subcortical nuclei linked to the thalamus involved in
control of movement, motor learning, executive functions and emotions.
Diencephalon: acts as a relay and processing centre for sensory information.
- Thalamus: Relay station for sensory information. White lamina (layers) composed of
myelinated axons lie on the surface of the thalamus. Thalamus contains different
pairs of nuclei that project to the cortex. The sensory relay nuclei receive signals
from sensory receptors, process them and transmit them to the appropriate areas of
the sensory cortex. They are not one-way streets but receive feedback signals from
the areas they project to.
- Hypothalamus: Involved in ‘homeostatic’ mechanisms; regulation of many
motivated behaviours (eg. eating, sleep, sex). This is done by regulating the release
of hormones from the pituitary gland. The optic chiasm (where optic nerves from
each eye come together) also appears on the inferior surface of the
hypothalamus.
Midbrain
Mesencephalon: divided into the tectum and tegmentum.
, - Tectum: dorsal surface of the midbrain. Composed of two bumps (colliculi). The inferior colliculi have an
auditory function. The superior colliculi have a visual-motor function.
- Tegmentum: ventral division of the midbrain. Contains the periaqueductal gray (gray matter around the
cerebral aquaduct), the substantia nigra and the red nucleus (both important components of the
sensorimotor system.
Hindbrain
Metencephalon: composed of ascending and descending tracts and part of the reticular formation.
Contains the pons and cerebellum.
- Pons: Structure that creates a bulge on the ventral surface of the brain
- Cerebellum: An important sensorimotor structure (involved in motor coordination). Damage to the
cerebellum eliminates the ability to precisely control movement and adapt them to changing conditions.
It also produces many cognitive deficits in decision making and use of language.
Myelencephalon (medulla): composed largely of tracts carrying signals between the rest of the brain and
body. It has a complex network of 100 tiny nuclei that occupies the central core of the brain stem from the
posterior boundary of the myelencephalon to the anterior boundary of the midbrain, called the reticular
formation. The caudal end develops into the spinal cord.
Four Lobes
- Frontal lobe: two distinct functional areas
o Precentral gyrus (+ adjacent frontal cortex): motor function
o Frontal cortex anterior to the motor cortex: performs complex cognitive
functions such as planning response sequences, evaluating the
outcomes of potential patterns of behaviour and assessing the
significance of the behaviour of others.
- Parietal lobe: divides into two large functional areas
o Postcentral gyrus: analyses sensations from the body eg. touch
o Posterior part of the parietal lobe: visuo-spatial awareness and attention.
- Temporal lobe: three general functional areas:
o Superior temporal gyrus: involved in hearing and language
o Inferior temporal cortex: identifies visual complex patterns
o Medial portion of temporal cortex: important for certain kinds of memory
- Occipital lobe: analysis of visual input.
Lecture 3 – Neurons
- Neurons are specialised cells that receive, conduct
and transmit electrochemical signals
- Neurons come in many shapes and sizes and are
supported by glial cells (nonneural cells) which
outnumber neurons by 10:1.
- Parts of a neuron include the soma, myelin sheath,
nodes of ranvier, cell membrane, dendrites, axon,
terminal buttons and synapses.
- Neurons communicate with each other via
electrical events called ‘action potentials’ and
chemical neurotransmitters.
- The process of neural communication:
o Electric potential in axon hillock (start of
axon) becomes more positively charged
(usually the neuron has a negative
charge) which triggers an electric impulse
known as ‘action potential’.
o Action potential travels down axon to terminal button
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