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Psychology 10003 > Behavioural Neuroscience > Flashcards

Behavioural Neuroscience Flashcards

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1
Q

First belief of brain (Egyptian times)

A

In Egyptian times, it was suggested the HEART was the seat of the mind

changing thoughts and beliefs were limited due to:

  • religious/moral beliefs
  • limited methods
  • reliance on chance discoveries (serendipity)
  • scientific conservatism (keeping with old traditions)
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2
Q

Hippocrates (460 BC)

A

Hippocrates was the first person to propose that the brain controlled the body

However, dissection of bodies was not permitted in ancient Greece thus he was only able to examine the brain in open wound injuries after a traumatic head injury

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3
Q

Galen (130 AD)

A

Galen demonstrated that nerves connected the brain to the body

Used VIVISECTION (dissection on live animals) to study anatomy of nervous system
Through this, he was able to distinguish between motor neurons and sensory neurons (cut a nerve near pig's neck that stopped the pig from squealing, indicating this nerve played a role in vocals)

Proposed the idea of PNEUMATA (‘spirits’) - animal spirits flow through the hollow nerves to and from the ventricles (fluid filled cavities in the brain)
3 types of spirits:
-Natural = resides in the liver, associated with nutrition and metabolism
-Vital = resides in the heart, regulates blood flow and body temperature
-Animal = resides in the brain, controls sensation and movement

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4
Q

Andreas Vesalius (1514 AD)

A

Able to map out detailed structure of the brain

  • revived vivisection and dissection after the dark ages
  • able to advance in brain structure but still had little understanding/explanation about how the brain works + pneumata theory still remained (no evidence to refute)
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5
Q

Luigi Galvani (1737)

A

Demonstrated that nerve signals are electrical and not fluid/hollow (found out on accident during a dissection of a frog)

Found that an electrical charge to a frog’s foot made it contract

  • Suggested that nerves must be coated by FAT to prevent electricity from leaking out
  • This evidence rejected the pneumata theory

Galvani used a FRICTION machine = a large disc that was cranked by hand which was rubbed against a surface to generate electrical charge
Charge was stored in a LEYDEN JAR = glass jar with a metal outer coating and liquid inside, covered with a rubber top

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6
Q

Franz Joseph Gall (1758)

A

Proposed idea of modular brain
-his ideas were influenced by PHYSIOGNOMY (art os ascribing personality was based on facial features)

proposed the brain was composed of several distinct ‘organs of thought’ or faculties (these groups are reflected by the characteristics patterns of bumps on skull; skull maps allow us to ‘read’ a person’s characteristics)
(remembered from child hood, a friend had very good verbal memory + bulging eyes; assumed bulging eyes are due to over development of frontal brain responsible for memory of words)

GALLS’ PHRENOLOGY = if one’s specific characteristic was great, it’s assigned section in brain would be enlarged, causing skull in that section to have a bump OR if characteristic was diminished, area in skull would be hollow
(flawed theory BUT was the introduced of cortical localisation of function + modular organisation of brain)

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7
Q

Paul Broca (1861)

A

Showed first solid evidnec of brain modularity

Had a patient that was unable to speak (had damage to left frontal lobe = Broca’s area leading to Broca’s Aphasia)

Wernicke’s aphasia = disorder of language comprehension (carl wernicke), unable to comprehend language but can still speak

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8
Q

Limitations of clinical neuropsychology

A
  • patients are hard to test intensively (patients are fatigued after trauma)
  • problem in replicating a single case (different patients may have big/small differences in leisions)
  • assumes local lesions have local effects (connections between brains may be controlling a behaviour, not just one section)
  • no control of lesion/size in brain
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9
Q

Electrical stimulation of animal brains

A

-discovery of precise localisation in cortical functions

Fritsche & Hitzig = electrically stimulated frontal lobes of dogs which induced contractions in muscles, on opposite side of body

  • when they removed the motor regions of the cortex, the limb was no longer able to contract anymore
  • motor region in frontal lobe was arranged SOMATOTOPICALLY (according to body parts)
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10
Q

Ablation studies

A

Ablation = deliberate lesions were done in the brain to allow fairly high degree of precision, demonstrating localisation of different parts of brains (unlike neuropsychology)

ablation studies on primates showed the LIMBIC SYSTEM:
contains small structures (hippocampus, amygdala) =usually whole structure or part would be damaged

using ablation, when removed the hippocampus, it showed to play a role in memory and learning (if amygdala was removed, no effect on learning + memory)

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11
Q

Egas Moniz

A

introduced prefrontal leucotomy (lobotomy) to provide relief for psychiatric disorders (making their behaviour more socially acceptable)
(based on Yale researchers that removed frontal lobes of chimpanzees that made them calmer)

Prefrontal leucotomy = a hole is drilled in the skull and a leucotomy was inserted (wire could have affected deeper tissues leading to consequences)
-personality consequences = apathy, emotional unresponsiveness, disinhibition, inability to plan

Was popularised in US by Walter Freeman (lobotomy)

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12
Q

Electroconvulsive Therapy (ECT)

A

based on the knowledge that seizures would decrease psychiatric symptoms
(early 1500s, seizure inducing agents were given to treat psychiatric conditions)

ECT is now mainly used to treat depression:
two electrodes are placed on both sides of temples which is controlled by a device that generates large, strong currents (causes seizures in frontal lobes)

Scalp-recorded electroencephalogram (EEG) = recording of brain activity during a seizure
-demonstrated epileptiform spikes (main diagnostic tests for seizures now)

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13
Q

Electrophysiological responses of single neurons

A

Hodgkin & Huxley was able to record the action potentials in the giant axon of a squid

This lead to development in micro electrodes, high gain electronic amplifiers, oscilloscopes

-dye can be injected into a neuron to see structure, whilst electrode is placed adjacent to neuron to measure electrical activity
(sensory + motor cortex was mapped using this technique)

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14
Q

Computerised tomographic (CT)

A

CT scans reveal brain structures by passing x-ray waves at different angles producing 3D images

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15
Q

Magnetic resonance imaging (MRI)

A

MRI physics:
-hydrogen is affected by magnetic fields, where proton and electron spin randomly
-in an MRI (strong magnetic field), all hydrogens align up to face the magnetic field
-when a RADIO-FREQUENCY PULSE is introduced, the axis of rotation of every atom is same and when turned off, they relax back in the previous direction (this gives off small amounts of energy that can be detected by MRI machine)
-tissues in the brain with lots of brain (least dense) = contains lots of hydrogen
therefore, energy given off by a particular area of brain depends on density of tissue (ranging in different structures)

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16
Q

Functional Magnetic Resonance Imaging (fMRI)

A

fMRI is a method that reveals brain structure in real time
-based on the idea that cognitive processes uses energy (energy from haemoglobin)

Oxygenated blood = weakly diamagnetic, doesn’t distort surrounding magnetic field
Deoxygenated blood = paramagnetic, distorts surrounding magnetic field

Blood vessels became more apparent in fMRI as blood oxygen decreases
BOLD effect: ratio between oxygenated and deoxygenated blood

red = oxygenated blood, blue = deoxygenated blood

When brain is about to be active, rush of oxygenated blood is supplied (anticipate activity). However, not all oxygenated blood would be used thus in the vein, there will be a mixture of oxygenated/deoxygenated blood

Benefits: provides specific information allowing for localisation of brain functions

Limitations: since it is based on blood supply (not electric signals), the changes are not so fast therefore, it is not efficient for brain activity that occurs fast

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17
Q

Transcranial magnetic stimulation (TMS)

A

(provides more causal links between localisation and brain functions)

TMS generates very strong magnetic field that can go through skull and brain tissues
-strong magnetic field can alter brain function in specific region of brain

TMS is also used to provide relief to psychiatric symptoms (placed on frontal lobes to provide relief)

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18
Q

Withdrawal reflex

A

Simple neural network that does not require conscious thought (we can respond quickly to dangerous situations)

In a withdrawal reflex, electrical signals from sensory neurons excite motor neurons by interneurons (in spinal cord) which then causes a muscular contraction
(signals causes neurotransmitters to be released, contracting muscles)

Electrical signal that was sent to brain has a possibility to returning back down, exciting interneuron, which may inhibit the interneuron activating motor neuron (muscular contraction can be prevented)

This depends on the excitatory/inhibitory level of both signals (excitatory signal from sensory neuron and inhibitory signal from an axon in the brain)

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19
Q

Typical neuron structures

A

Dendrites - electrical signal is received here

Cell body - control centre of neuron, provides necessary energy/nutrients

Axon terminals - where electrical signals output, may influence next neuron

Glial cells = physical/mechanical support to neurons, assists with chemical transport, providing insulation, destroy/remove dead cells

  • Astrocyte = glial cells supporting blood vessels + house keeping
  • Schwann cells = makes up the myelin sheath (present in PNS)
  • Oligodendrocytes = produces myelin sheath in CNS
  • Microglia - smallest type of glial cells that attacks microorganisms (responsible for brain swelling)

(cell membrane of neurons are made up of phospholipids = separates fluids from inside and out)

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20
Q

Membrane potential

A

(we can use microelectrodes to measure the difference of potential inside and outside of neuron + can inject voltage)
Resting potential = -70 mV inside neuron
(3 sodium out, 2 potassium in)

Depolarisation and Repolarisation
-Depolarisation = threshold potential was reached at -55 mV causing an action potential
Depolarisation causes Na+ channels to open, allow Na ions to come in, causing inside of neuron to become slightly more positive
Change of charge moves down along axis

Repolarisation
K channels open after sodium where potassium ions can rush out, changing inside of neurons to become more negative
Potential decreases back down

Refractory period/Hyperpolarization

  • undershoot in potential (below resting period) occurs as potassium ions can leak out faster than sodium ions coming in + neuron is unable to generate another action potential during hypolarization
  • refractory period is where potential is returned back to resting potential
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21
Q

Saltatory Conduction

A

Saltatory conduction = to hop

Propagation of action potentials down an axon (increases the conduction velocity of action potential)

Node of Ranvier (where channels are found; in between myelin sheaths)

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22
Q

All or none law of action potential

A

How much an input of excitation in a neuron, controls whether neuron generates an action potential (strength of neuron is not dependent on strength of stimulus)

All or none amplitude = no matter the depolarisation/energy input, the amplitude of an action potential will always be same

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23
Q

Rate law of action potentials

A

Message of a stimulus is depicted by the number of action potential generated rather than ‘strength’ of action potential (amplitude)

Stronger stimulus = more action potentials fired

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24
Q

Multiple Sclerosis (MS)

A

An autoimmune disease that affect the insulation of neurons (myelin sheath) affecting ability of electrical signals to pass through

Leads of visual problems, numbness of body, weakness of limbs that can lead to paraplegia (paralysed from waist down), slurred speech, problems with vision and eye movements

Multiple ‘attacks’ are either followed by remission or quiescence (inactive/dormant)
(if shown a diagram of brain, there are spots of whites (which should be grey, but white to stand out) to indicate missing myelin sheath)

When action potential moves down an axon, due to lack of myelin sheath, it has the potential to leak out leading to not enough potential to generate an action potential (electrical signal is stopped)

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25
Q

Structure of a synapse

A

Presynaptic cleft = where signals arrive + where neurotransmitters are released into synaptic cleft through synaptic vesicles (synaptic vesicles are guided by microtubules)

Dendritic spine - structure along the post synaptic cleft that ensures the physical distance between pre and post cleft is very small

Ionotropoic receptors - membrane bound receptors found on post-synaptic membrane which are neurotransmitter dependent (binding of neurotransmitter opens channel, allowing ions to move in) dependent on which ionotropic receptors are activated

  • Flow of SODIUM IONS = causes membrane to be more positive than outside which increases likelihood of an action potential to be triggered = EXCITATORY POSTSYNAPTIC POTENTIAL
  • Flow of POTASSIUM OUT or CHLORIDE IN IONS = causes membrane to be more negative than outside, decreasing likelihood of action potential = INHIBITORY POSTSYNAPTIC POTENTIAL

Excitatory postsynaptic potential (EPSP) = increases likelihood that action potential is triggered in post synaptic
Inhibitory postsynaptic potential (IPSP) = decreases likelihood that action potential is triggered

NEURAL INTEGRATION = combined effects of EPSP and IPSP (e.g. neutralised withdrawal effect due to signal from brain)

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26
Q

Effect of drugs on synaptic functions

A

Agonists = facilitates activity of the postsynaptic membrane

  • increases synthesis of neurotransmitters
  • increases release of neurotransmitters in vesicles
  • drug can either can activate receptors or increase/enhance effect of neurotransmitters
    e. g. L-dopa = increases synthesis of dopamine (used to treat Parkinson’s (motor abilities), affects basal ganglia)
    e. g. Nicotine = stimulates acetylcholine receptors (found on muscles = causes lots of twitching in heavy smokers)

Antagonists = inhibits activity of post synaptic membranes
-blocks synthesis of neurotransmitters
-blocks release of neurotransmitters into synaptic cleft
-binds to receptor, blocking neurotransmitters
e.g. PCPA (drug solely used to see effect of serotonin on brain activity, inhibits synthesis of serotonin
Botulinum (botox) = binds/blocks release of acetylcholine (paralysis in muscles = less wrinkles)

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27
Q

Classes of neurotransmitters

A

Amino acids –> glutamate (most common excitatory neurotransmitters), GABA (inhibitory)

Monoamides = catecholamines (dopamine, norepinephrine), indolamines (serotonin) = mostly present in neurons in brain stem

Acetylcholine

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28
Q

Neurotransmitter projection pathways

A

Dopamine, serotonin, norepinephrine, histamine are all produced in the nuclei of brainstem, where they are used in different parts of the central nervous system (regulating different brain functions)

Dopamine = produced in substantia nigra (not used in cerebellum = not projected there)

Noradrenaline = made in locus coeruleus

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29
Q

Neural axis of body/brain

A

Dorsal (superior) - towards the back, top side facing up
Ventral (inferior) - towards the stomach/belly, top side (belly) facing down
Rostral (anterior) - towards the beak, front
Caudal (posterior) - towards the tail, behind

Human neuraxis - axis bends as head bends 
Lateral - towards the sides
Medial - towards the midline
Ipsilateral - same side (one sided)
Contralateral - opposite sides
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30
Q

Division of Nervous System

A

Central nervous system - spinal cord and brain

Peripheral nervous system (spinal and cranial nerves):

  • Somatic system (connects central system to voluntary muscles)
  • Autonomic system (connects central system to non-voluntary muscles and glands)
  • Sympathetic system = excitatory, prepares body for activity
  • Parasympathetic system = inhibitory, prepares body for restoration of energy
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31
Q

Tissues of Brain

A

Entire nervous system is covered by protective sheath of connective tissue = MENINGES

  • Dura mater = tough outer layer
  • Arachnoid mater = middle layer that has weblike appearances due to Arachnoid trabeculae, is soft and spongy, allows cerebrospinial fluids to flow through (subarachnoid space)
  • Pia mater = delicate inner layer than conforms to folds of brains

Peripheral = DOES NOT HAVE ARACHNOID MATER

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32
Q

Cerebrospinal fluids (CSF)

A

Clear fluids that supports brain and reduces shock due to head movements

CSF is produced by CHOROID PLEXUS located in lateral ventricles (open spaces)
Fluids flow down to third ventrical, then cerebral aqueduct to the fourth ventrical then exits to circulate through subarachnoid space
It is constantly reabsorbed into bloodstream by arachnoid villi (as it is constantly produced)

Lateral ventricles are connected by the third ventricle which goes down into cerebral aqueduct and fourth ventricle (directly below the cerebellum)

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33
Q

Forebrain

A

Forebrain has two divisions - Telencephalon and Diencephalon

TELENCEPHALON:

  • composed of two cerebral hemispheres = together is the cerebrum
  • outer layer = cortex
  • inner tissues = basal ganglia and limbic system
  • White matter (under cortex) = axons that are myelinated
  • Grey matter = only contain neural cell bodies

Fissures = deep groves in brain
Sulcus = smaller grooves (gives distinct patterns of brains)
-CENTRAL SULCUS = distinct groove, found on both hemispheres, that extend from top of middle section to the midbrain
Gyrus (gyri) = bulging region of tissue

DIENCEPHALON:
-surrounds the third ventricle, in the middle of brain
-consists of Thalamus and Hypothalamus
THALAMUS:
-dorsal part
-relay station for sensory information being conveyed to cerebral cortex
-divided into smaller nuclei which are specific
(lateral geniculate nucleus = receives information from retina of eye and sends down to axons in primary visual cortex
medial geniculate nucleus = receives from inner ear and sends axons to primary auditory cortex)

HYPOTHALAMUS:
under thalamus
-controls endocrine system and autonomic system
-also regulates behaviour for survival (fighting, fleeing, feeding, mating)

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34
Q

Lobes of Cerebral Cortex

A

Frontal lobe:

  • contains all cortex anterior of central sulcus
  • large in humans
  • responsible for planning, reasoning, reflection on behaviour

Parietal lobe:

  • cortex posterior (behind) of central sulcus
  • behind frontal lobe, on top of temporal lobe
  • left: plays a role in mental arithmetics and language comprehension
  • right: role in representing salient objects in space

Temporal lobe:

  • posterior or frontal lobe and ventral of parietal lobe
  • left: understanding spoken language and written words
    right: involved in recognising complicated objects and faces

Occipital lobe:

  • caudal (behind) parietal lobe and temporal lobe
  • cortex in this area processes visual information (motion, colour, shape)

Some functions are lateralized to one hemisphere = hard to describe complex, specialised function of each hemispheres

Left can be thought as: responsible for analytical processing of information (breaking down to make sense)
Right: specialised in synthesis of information, putting wholes together from different parts

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35
Q

Primary somatosensory cortex

A

The Primary Somatosensory Cortex is the strip of cortex right behind the central gyrus = POSTCENTRAL GYRUS
It receives information from the skin (temperature, pain, touch)
Different regions on skin correlates to different sections of cortex = somatotopic map

Somatotopic map = sensory homunculus
there is a structured order of body parts by which section of cortex (large section is associated with lips, mouth, face whereas trunk of body = small sections)

36
Q

Primary visual cortex

A

Area of cortex that occupies the medial and lateral sections of occipital lobe

  • Receives information from the retina
  • Different sections of cortex corelates to different sections on retina = retinotopic map
37
Q

Primary auditory cortex

A

Strip of cortex below the SYLVIAN FISSURE (ridge in the middle of brain)

Different sections receives information from different parts of cochlea = tonotopic map (arranged from lower frequencies to higher frequencies)

Contralateral = information from right ear goes to left hemisphere (contralateral connections are stronger evne though information is delivered to both hemispheres)

Secondary auditory cortex = takes signals from primary to process further, giving us a more complex understanding (damage = aphasia, inability to comprehend language)

38
Q

Primary motor cortex

A

Is strip of cortex ANTERIOR OF CENTRAL GYRUS (in front)

different sections control different VOLUNTARY muscles (works contralaterally)

parts of the cortex that is not associated with intial sensory reception or voluntary muscle control is associated with perception, learning, memory, planning, acting, feeling = ASSOCIATION AREAS

39
Q

Higher order functions of frontal lobes

A

Humans have larger frontal lobes compared to other animals = more complex, higher order functions

  • voluntary, controlled behaviour
  • language
  • abstract thinking + reasoning
  • impulse control + emotional regulation
  • social cognition

higher connections of prefrontal cortex to reset of brain = correlates to working memory (we can retain information for abstract thinking + decision making)

40
Q

Corpus Callosum

A

Large bundle of axons connecting left hemisphere to right = Corpus Callosum

Homotopic = some axons in the same region/cortex on both hemispheres
Heterotopic = axons leading to different region/cortex on both hemispheres
Ipsilateral = axons leading to different region/cortex in the same hemisphere

CALLOSOTOMY = corpus callosum surgically cut to stop epiletic seizures (stopping abnormal electrical signals spreading from one hemisphere to another)
-asking one to pick up something with right hand = language comprehension (left hemisphere), will say that can pick it up but not actually

-asking someone to pick up with left hand = uses right hemisphere (not comprehending language, but still picking up another object)

41
Q

Limbic system

A 
Is found in medial portion of both hemispheres
Contains:
-amygdala
-hypothalamus
-formix
-mamillary body
-cingulate gyrus
42
Q

Basal Ganglia

A
  • plays a role in involuntary movement (walking, running etc, autonomic)
  • collection of cell bodies of neurons (grey matter), even though not considered a part of cerebral cortex
  • is located in precentral gyrus

consists of:

  • Caudate nucleus
  • putamen
  • globus padillus
43
Q

Midbrain

A

(Mesencephalon)

  • towards base of the brain (junction between cerebrum and spinal cord)
  • more evoutionary old structures

TECTION (TOP SECTION OF MIDBRAIN)
Superior and inferior colliculus = may play a role in auditory + visual processing, spatial awareness

TEGMENTUM (BOTTOM SECTION OF MIDBRAIN)
Reticular formation - regulating arousal (ability to remain conscious/alert, damage = coma), sleep, various reflexes 
Substantia Nigra (black substance, grey matter) = cell bodies produce dopamine (affects basal ganglia)
44
Q

Hindbrain

A

Hindbrain is separated into metencephalon and myelencephalon
-important in autonomic regulation

METENCEPHALON - important in arousal, sleep, relaying information to/from cerebellum via cerebellar peduncles
Pons = top section (right below superior/inferior colliculus)

Myelencephalon = medulla (connects hindbrain to spinal cord)

CEREBELLUM:

  • highly folded surface to hold lots of neurons in a small space
  • responsible for skilled movement without consciousness + changing motor movements to unexpected environments (e.g. body changes position and send signal to cerebellum to automatically makes changes to body positions. acts without conscious thought = without we will fall a lot)
  • consists of outer cerebellar cortex and inner deep nuclei
45
Q

Spinal cord

A

Spinal cord is contained within a spinal column made up of 24 individual vertebrae stacked on top of each other
Cerival vertebrae = neck
Thoraric vertebrae = back
Lumbar vertebrae = lower back
Sacral vertebrae = pelvic region (vertebraes are fused together)

Spinal column protects the spinal cord
Spinal foramen = hollow channel running down spinal column containing the spinal cord

Spinal cord consists of grey matter surrounded by white matter

Groups of axons can bundle in the sides of spinal cord = dorsal root (from dorsolateral side of spinal cord) or ventral root
Pair of roots come together to form a SPINAL NERVE
31 PAIRS OF SPINAL NERVES (receives information from sensory receptors and sends signals from brain to glands/muscles)

Dorsal root ganglion - cluster of neurons found in dorsal root (AFFERENT neurons, brings informations TO CNS)
Ventral root = EFFERENT neurons (cell bodies that deliver information to glands/muscles from brain)

46
Q

Sympathetic and Parasympathetic (ANS)

A

Cell bodies of sympathetic motor neurons are found in thoraric and lumbar regions

  • axons of these neurons exits the spinal cord by ventral roots
  • they pass to a chain of sympathetic ganglia that are connected to neighbour above and below, forming the SYMPATHETIC GANGLIA CHAIN (parallel to spinal cord)

Cell bodies of PARASYMPATHETIC neurons are found in some cranial nerves + grey matter in sacral region

47
Q

Physical and Perceptual Dimension of Sound

A

Actual loudness is based on AMPLITUDE of sin wave (perceptual dimension)

Pitch of sound is based on FREQUENCY of sound waves (slower/less sound waves = lower pitch)

Timbre of sound is based on COMPLEXITY of sound waves (complex sounds = range of sound waves with different amplitudes)

48
Q

Structure of ear

A

-sound waves enter through the auditory canal (pinna helps sound waves enter, bounces till they reach canal), causing the tympanic membrane to move forwards and backwards

OUTER EAR:
pinna - directs sound waves into auditory canal
Auditory canal
tympanic membrane (eardrum) - vibrates forwards and backwards, connected to ossicles

MIDDLE EAR:
ossicles - three tiny bones (malleus, inctus, stapes), are held in position by muscles on top, vibrations causes movement to cochlea (stapes is connected to oval window of cochlea)

INNER EAR:
cochlea - filled with fluid that moves around due to in/out motion of oval window, circle window bulges in/out when fluids are moving around

49
Q

Structure and Function of Cochlea

A

Cochlea contains basilar membrane which runs from base to apex (top), in a circular direction (basilar membrane is in the centre of cochlea)

  • higher frequency tones are closer to basal end
  • lower frequency tones are close to apex end

Organ of Corti - structure we see in cochlea if it was cut horizontally = 3 inner chambers

  • Organ of corti is found on the floor of the middle chamber
  • Composed on basilar membrane at the base
  • Receptors in the middle (on top of basilar membrane), hair cells (inner and outer hair cells)
  • Rigid shelf over the top = tectorial membrane

On top of the hair cells, there are even smaller tiny filaments = stereocilia
Movement of fluids in cochlea causes basilar membrane to move, where bending the stereocilia by direct contact with tecotorial membrane or fluid motion due to movement of basilar membrane
-bending of stereocilia causes receptor potentials in hair cells = release of neurotransmitters = action potentials

Action potentials are sent to spiral ganglion cells (grouped up spiral ganglion cells = auditory nerves)
Axons of auditory nerve are connected to medulla (brain stem) then sent to corresponding sections for processing
-most of auditory nerves are connected to inner hair cells
-outer hair cells are thought to be effector cells, changing the mechanical position of basilar membrane thus affecting effect of sound waves on inner hair cells

50
Q

Electromagnetic Spectrum

A

Visible wavelengths = 380nm - 760nm

Traits of colour:
Hue - wavelength of electromagnetic radiation
Brightness - intensity of electromagnetic radiation
Saturation - purity of electromagnetic radiation

51
Q

Human Eye

A

-transducing light into a neural signal

Light enters eye by CORNEA where the layer behind the cornea is the LENS (can stretched or relaxed to help focus image in the back of the eye)
Light shines onto the RETINA
(eyeball itself is filled with vitreous humour)
Axons from rods and cones all meet up at OPTIC DISK = blindspot (no cones/rods present)
Axons all bundled up forms the OPTIC NERVE
-in the fovea, cones are highly concentrated (no rods), most sharpest image/spot on retina

Cells of retina:

  • Photoreceptor cells are at the back –> bipolar cells –> ganglion cells
  • Photoreceptor cells are connected to bipolar cells through HORIZONTAL CELLS
  • Ganglion cells are connected to bipolar cells through AMACRINE CELLS
  • In photoreceptor cells, there are photopigments which break down when exposed to light triggering a pathway –> action potential
52
Q

Visual Pathway to the Eye

A

S cones = blue light (440 nm)
M cones = green light
L cones = red light (560 nm)

When light passes through, it either hits the TEMPORAL RETINA (near temple) or NASAL RETINA (closest of nose)
-Axons move towards the back and medially where axons from both eyes meet = OPTIC CHIASMA
-~50% of axons cross over to other side
(signals from temporal retina stays in the same direction (e.g. right visual field hits left temporal retina = left hemisphere))

Axons form synapses with the LATERAL GENICULATE NUCLEUS which are connected to the primary visual cortex (90% of signals)
~10% of signals are projected to other areas like SUPERIOR COLLICULUS and pulvinar nucleus of thalamus

53
Q

Cone responses to light

A

Ganglion cells are excited by a group of photoreceptors = excited by small region of the visual field which is the RECEPTIVE FIELD

Receptive field of ganglion cells have a CENTRE-SURROUND ORGANISATION where ON cells are excited by light in the centre and inhibited by light in surroundings ; OFF cells are excited by light in surrounding and inhibited by light in the centre
= allows the signalling of edges and borders giving us higher order visual perception

E.g. with a picture of a banana
If we combine the orientation of ON cells to where most of the light is reflected on the banana, most of the signals are excitatory

There is orientation selectivity of the receptor fields
LGN = centre-surround organisation (circles on top of each other)
V1 = prefers vertical field (negative-positive-negative)
If bars/edges in field is in preferred orientation, more action potntials will be fired (e.g. V1 prefers vertical stimulus)

54
Q

Modular Organisation of Primary Visual Cortex

A

Primary visual cortex is sectioned into different functional modules that have axons for specialized information

V1 = primary visual cortex region
V4 = region sensitive to colour
MT = region that is response to moving stimuli
Inferior temporal cortex = selectively responds to complex objects and faces

55
Q

Hemianopia

A

Damage to V1 (first region to receive axons from visual cells from lateral geniculate nucleus)

  • works contralaterally
  • damage can occur due to stroke = no blood supply to region causing cell death (posterior cerebral artery)
  • if V1 area is damaged, all visual field corresponding to the contralateral side will be blind

Hemianopia = loss of vision in one side

PERIMETRY TEST is done to see whether you have damage to V1 area (looking into a semi circle ‘bowl’ where flashes appear and you click every time you see the flashes)

56
Q

Hemiachromatopsia

A

Damage to V4 area = unable to perceive colour in contralateral side

57
Q

Akinetopsia

A

Damage to MT area = losing ability to perceive motion

58
Q

Visual Object Agnosia

A

Damage to temporal cortex = inability to detect/recognize familiar objects

-Can still recognise through other senses = hearing and touch

59
Q

Face Inversion Effect

A

We are able to easily recognise faces by putting them together, however when they are upside down, it is hard to recognise
(when other objects are upside down, it is not as difficult to learn which way they are shown)

  • Suggested that specific sections of the ‘inferior temporal cortex’ processes the subtle differences in eyes, eyebrows, mouth, nose to put together a face
  • when face is inverted, the configurations with facial parts are altered (e.g. eyebrows are below the eyes now)
60
Q

Prosopagnosia

A

Face blindness

-fusiform gyrus (part of temporal lobe)

61
Q

Emotion

A

Emotion consists of physiological response and species-specific responses/behaviours

  • In humans, physiological responses are accompanied by feelings
  • feelings are strong motivators = play a role/influences how we are most likely going to behave in particular situations

Emotions are likely to have an evolutionary significant = if behaviour/expressions benefit the organism, they may evolve in ways that enhance their communicative value

  • like displaying the intention to fight but not actually engaging = may lead to fewer deaths
  • expressions/behaviour must be easily recognizable and distinguishable
62
Q

Components of emotional responses

A

1 - Behavioural

  • muscular changes that are appropriate to the situation that elicits them
    e. g. dogs adopting an aggressive posture (growling, ears forward, tail up) = easily distinguishable

2 - Autonomic

  • physiological changes induced by the autonomic nervous system that aids the behavioural responses
    e. g. heart rate increasing

3 - Hormonal

  • hormonal changes that reinforce autonomic changes
    e. g. adrenal glands release epinephrine and norepinephrine
63
Q

Neural Control of Emotional Response patterns (Bard)

A

Bard carried out ablation studies on cats

-removal of cerebral cortex caused cats to act in excessive aggressively manner to stimuli/events that would not usually cause rage = sham rage
(decortication = removal of both hemisphere cerebral cortex)

-removal of hypothalamus caused cats to no longer demonstrate sham rage

= hypothalamus is response for expression of aggressive behaviour
= cerebral cortex is responsible for controlling, expression of emotional responses

64
Q

Kluver-Bucy syndrome and amygdala

A

Kluver and Bucy did ablation studies on rhesus monkies by removing the temporal lobes

  • monkeys ate anything = hyperphagia
  • were more sexual (on inappropriate objects)
  • explore all items with their mouths = ‘psychic blindness’ (impaired visual recognition)
  • ABSENCE OF FEAR (completely tame after surgery = to humans, snakes, cats)
65
Q

Structure of Amygdala

A

Located in the anterior temporal lobe

Medial nucleus = receives sensory inputs (+ information from olfactory system) and relays information to the basal forebrain and hypothalamus

Lateral/basolateral nuclei = receives information from primary sensory cortex, association cortex, thalamus and hippocampus.
Sends axons to parts of basal ganglia, thalamus and central nucleus of amygdala

Central nucleus = sends axons to hypothalamus, midbrain, pons and medulla that are responsible for expression of emotional responses

Basal nucleus = receives axons from lateral and basolateral nucleus, sends axons to other amygdaloid nuclei and to midbrain

Central nucleus = most important
(lesion = loss of fear to stimuli
agitation = enough to initiate fear)

66
Q

Anxiolytic drugs on amygdala

A

Anxiolytic drugs are anxiety-reducing which affects the central nucleus of amygdala

-central nucleus has lots of opiate receptors = reduces activity/blocks

67
Q

Phineas Gage and Frontal Lobe

A

Patient that survived a metal rod through his frontal lobe

  • emotion and character has changed drastically after accident
  • became profane, impatient, irrational, unable to plan for the future, unable to do his previous jobs
  • required jobs that have no decision making
68
Q

Orbitofrontal cortex and decision making

A

Orbitofrontal cortex is located on the underside of the frontal lobes (above the orbits that contain the eyes)
= VENTROMEDIAL PREFRONTAL CORTEX

  • involved in social and emotional decision making
  • processes, filtrates, evaluates social and emotional information = being a guide to our behaviour
  • damage = impairs decisions that rely on emotion or social cues
69
Q

James-Lange Theory

A

An emotion-inducing stimulus cases bodily, physiological changes (increased breathing, heart rate) that then generates emotions

  • brain receiving feedback from sensory receptors causes the emotional feelings
  • emotional feelings are determined by the way we interpret sensory feedback we receive from our physiological response
70
Q

Cannon-Bard Theory

A

(in response to James-Lange as physiological changes/organs are slow which does not match immediate emotional feelings)

emotion-inducing stimuli has two INDEPENDENT effects: emotional feelings + physiological effects (somatic and autonomic system)

71
Q

Schachter and Singer’s Two-Factor Theory of Emotion

A

-emotional inducing stimulus (vision arousal) was necessary but emotion experienced is based on individual’s INTERPRETATION of the experience (current environment context, thoughts and memories)

  • different emotional experiences reflect the variety of ways in which a common physiological response can be interpreted
  • feelings = interaction between physical arousal and the cognitive label given to the arousal
72
Q

Orbitofrontal cortex and somatic marker hypothesis

A

-Decision making is guided by emotional evaluation of the consequences of our actions

DAMASIO (1994) = we make decisions relying on the recollecting of the outcomes of previous choices

  • somatic marker = gut feeling, associating to previous emotional experience to a decision
  • somatic markers helps us anticipate the emotional consequences of our choices
73
Q

Effects of amygdala lesions on conditioned fear responses

A

Amygdala BLOCKS the ability to learn a conditioned reponse (fear) to a neutral stimulus

PHELPS ET AL (1998) - a woman with bilateral lesions of amygdala showed that she demonstrated fear to a shock + increase in skin conductance response (SCR), but was able to link the blue square shown before the shock

-participant as aware of relationship but demonstrated no changes in autnomic responses

74
Q

Amygdala Pathways and Fear Conditioning

A

Information can reach the amygdala via two different pathways

-Low road = information that is transported from sensory thalamus DIRECTLY to the lateral nucleus of amygala
(quickly, unregulated, no conscious recognition)

-High road = information from the sensory thalamus to primary sensory cortex, association cortex which process and analyze before sending to the lateral nucleus of the amygdala

75
Q

Lie Detectors

A

Measures the physiological changes of the person (activity of autonomic system)

Control-question technique:

  • not as accurate as you can get false positives
  • 80% detection
  • comparing physiological changes to base line of physiology (by asking neutral questions)

Guilty-knowledge technique

  • NO false positives + 88% of detection
  • questions are related to only information only a guilty person would know (innocent = same physiology whereas guilty will have changes)
76
Q

Concept of attention

A

The withdrawal of some things in order to deal effectively with others

77
Q

Blindsight (damage to V1)

A

Blindsight = disorder of normal vision

Scotoma = small patch of blindness due to small unilateral lesions of V1

Homonymous hemianopia = complete blindness in one visual side (unilateral destruction of V1)

Cortical blindness = complete loss of vision of both fields (total destruction of V1)

BLINDSIGHT = Weiskrantz showed that they may have lost vision experience, but they still have visual capacities (pupillary reflexes, manual and saccadic localisation, wavelenght and motion discrimination, orientation and shape discrimination)

78
Q

Perimetric test (blindsight, Weiskrantz)

A

Using perimetry task, the blind region was able to be established (unable to press when he saw spots in the specific region)

(blind spot was on left = damage to right hemisphere)

2nd study - showed flashes in blind region and was required to GUESS whether the flash was present of absent
=patient DB was able to get higher accuracy than 50% even though he had no conscious perception
(one region only had 43% = optic disc due to no photoreceptors in that section of retina)

79
Q

Visual Information to Brain (BLINDSIGHT)

A

Geniculostriate pathway = axons from lateral geniculate nucleus (LGN) to primary visual cortex

Axons to the superior colliculus (midbrain) and pulvinar nucleus of thalamus
-activity to SC (orientation response to sudden visual/auditory stimuli) and pulvinar is responsable for visual capacities in blindsight patients

80
Q

What is attention?

A

Key aspects of attention:

  • can be selective (spatial - item in the visual field, temporal - information at a given time, motoric - focusing on a task/body part)
  • capacity limitation (limited attention)
  • limit to vigilence (period of effective sustained attention)
  • perceptual set (expectations or maintenance of expectations, focusing on relevant/required information)
  • switching (attention is essential for switching tasks/environments)
81
Q

Hermann von Helmholtz - covert selective attention

A

Investigation on selective attention to see how much visual information can be processes in brief glimpses

  • large screen with letters (dark room, light on poster)
  • kept vision on the centre of screen but COVERTLY ATTENDED to another section of the screen without moving his eyes
  • was able to discriminate all the letters in the covertly attended area

=voluntary allocation of attention can enhance perception of stimuli in a specific area despite the receptors (retina/vision field) being fixated

82
Q

Michael Posner - spatial attention and neural processing speed

A

Task to quantify the effects of spatial attention on perception

-had to press button as fast as possible when saw the target
-shorter response times = faster processing
-valid trials = arrow facing towards target
invalid = arrow facing wrong direction
neutral = arrow pointing both ways
-valid trials had fastest response time

= ATTENTION can enhance information processing

83
Q

Goldberg - attention affecting neurons in parietal cortex

A

Goldberg mapped the receptive field of individual neurons as monkeys fixated on a central spot (irrelevant stimulus)

  • when a stimulus was flashed in the receptive field, the parietal cells showed small increase of rate of firing
  • second study, monkey had to release a lever when they detected a brief dimming of the stimulus
  • neurons fired much more faster = visual stimulation was increased when monkey covertly directed his attention

parietal neurons change their rate of firing, according to the attentional demand of the task

84
Q

Damage to parietal lobe = Unilateral spatial neglect

A

Unilateral spatial neglects occurs after damage to one side of brain (usually the right hemisphere)

-patients behave as if affect side does not exist (contralesional side)
(ignore food on one side, only doing makeup on one side, bumping into objects on one side)
-patients with unilateral spatial neglect, have NO AWARENESS of blindness

85
Q

Clinical tests of spatial neglect

A

MRI = can show damage to lobes

Sketching tasks = asking to cross shapes (only crosses on one side)
asking to indicate midpoint of a line (skews to one side)
drawing familiar objects (anomalies on left/right side of drawing)

  • when alerted to their answers, they were able to shift towards spatial neglected side = those with spatial neglect have loss of conscious perception
  • entire parietal lobe is required to determine where stimulus goes to make an image whole
86
Q

Neuropathology of Neglect

A

Spatial neglects occurs most frequently to those with lesions in (strokes) right hemisphere (particularly the INFERIOR PARIETAL LOBE)

other sections that is associated with spatial neglect are superior temporal gyrus, inferior frontal gyrus, middle frontal gyrus

87
Q

Unconscious perception in spatial neglect

A

Patients have demonstrated unconscious processing of neglected information (even though they lost conscious perception)

study: patient was asked to judge whether two houses, vertically aligned, were different
- if fire on house was on the right side = different (patient was able to discriminate)
- if fire was on the left side of house = same (patient neglected left side of stimuli = based on the right side)

patient asked which would you live in

  • right side flame = chose the normal house
  • left side flame (even though they both are ‘same’) = chose the house without fire

DEMONSTRATED THAT in the absence of conscious perception in neglect, some aspects of neglected information was unconsciously processed

  • likely to be sent through object recognition pathways of temporal lobe (from primary visual cortex)
  • damage to parietal lobe impairs selective attention = patients are UNAWARE of perceptual inputs on affected sides, but object recognition pathway will function normally
  • object identity processing will occur without patient’s explicit knowledge

Psychology 10003 (3 decks)

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