brain and behaviour - Details

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The sense in which properties of the outside world are copied/stimulated by cognition

Mental representation

The way in which properties of the outside world manifest themselves in the neural signal

Neural representation

The soul is confined to the body like it is a prison, so the soul seeks truth through organs of the body, specifically organs of perception. the brain is the immortal souls natural place

Plato's historical perspective

Psyche is a nonmaterial entity responsible for human consciousnesss, perceptions, emotions, imaginations, desire, pain, memory and reason. behaviour is controlled from the heart

Aristotle historical persepctive

Soul controls movements of the muscles through influence on the pineal body. uses dualism: mind (eternal) and body (mortal) are seperate substances.

Descartes historical perspective

Eighteenth-century Italian physiologist found electrical stimulation of frog's nerve caused contraction of attached muscle. - Galvani’s experiment prompted others to study nature of message transmitted by nerve and means by which muscles contracted. found ability of muscle to contract and ability of nerve to send a message to muscle, - Brain did not inflate muscles by directing pressurized fluid/air through the nerve (balloonist theory)

Luigi galvani

Violent epileptic seizures can be treated with surgically splitting the corpus callosum. corpus callosum connects the two hemispheres and is made up of a bundle of nerve fibres. found language production and right side motor control is in the left hemisphere.

How to study human consciousness - using split brains - sperry et al.

When testing one hemisphere, stimulus must be presented for 150 ms or less as this is faster than the eye can move from central fixation to the stimulus

How to control loss of lateralization within cognitive testing of the hemispheres

Right visual field will verbally give answer of the stimuli, but left visual field will say they can't see anything

Testing lateralization for visual stimuli

Out of a selection of objects, if the left hand picks the object its because the right hemisphere visualising it and controlling the left hand.

Testing lateralization for tactile stimuli

Recording, non-invasive, electrical. measures electrical activity of the brain through electrodes placed on the scalp. EEG signals represent the the change in the potential difference between two electrodes placed on the scalp. - The EEG obtained on several trials can be averaged together time locked to the stimulus to form an Event-Related Potential (ERP). ERPs are voltage fluctuations that are associated in time with particular event or stimulus (visual, auditory, olfactory stimuli). - When populations of neurons are active in synchrony, they produce an electric field that can be detected at the scalp (EEG). When many waves are averaged and linked to the onset of the stimulus, then an ERP is obtained

Electroencephalogy (EEG)

Different ERP peaks associated with different aspects fo face processing. n170 is relatively specialised for faces. p250 is for famous and familiar faces. ERP categorised by N and P which is positive and negative. a markedly reduced p300 is seen within dementia'alzheimer's patients. An ERP is an electrical signature of all different cognitive components that contribute to processing of that stimulus. Systematically varying aspects of a stimulus (e.g. any face vs. famous face) may lead to variations in aspects of ERP waveform. This can tell us about the timing and independence of cognitive processes

Using ERP to study face recognition

Recording, invasive, electrical Electrodes, consisting of thin wires, are implanted into specific areas of the brain. Recordings of brain cell activities are made by measuring the electrical potential of nearby neurons that are in close proximity to the electrode.Very tiny signals, so has to be amplified. cant use in humans.

Single cell (and mutli-unit) recordings

Stimulation, non-invasive, electromagnetic A means of disrupting normal brain activity by introducing neural noise – ‘virtual lesion’ experiment: if behaviour changes after stimulation it means area is necessary for task, if behaviour stays the same after stimulation then it shows the area only supports. applying TMS pulse at cortical node of network, then efficacy of that signal will be degraded, behavioural decrement (Speed of response) will change, and it will take us longer to read. but advantages of TMS are the virtual lesion technique, transient and reversible, control location of stimulation and establishes a causal link of different brain areas and a behavioural task.

TMS - transcranial magnetic stimulation

Recording, non-inavsive, electromagnetic imaging technique used to measure the magnetic fields produced by electrical activity in the brain via extremely sensitive devices known as SQUIDs. These measurements are commonly used in both research and clinical settings. Excellent temporal and spatial resolution.

MEG - - Magnetoencephalography

Recording, invasive, hemodynamic -radioactive tracer tracked to measure volume of blood that flows to the brain. - uses trace amounts of short-lived radioactive material to map functional processes in the brain. When the material undergoes radioactive decay a positron is emitted, which can be picked up be the detector. Areas of high radioactivity are associated with brain activity

PET - positron emission tomography

Recording, non-invasive, hemodynamic - Used differential magnetic properties of types of tissue and of blood to produce images of the brain - Structural: different types of tissue (skull, gray matter, white matter, CSF fluid) have different physical properties – used to create STATIC maps (CT and structural MRI) - Functional: temporary changes in brain physiology associated with cognitive processing (PET & fMRI)

Magnetic resonance imaging - MRI

Scanning builds up a picture of the brain based on the differential absorption of x-rays. reveals gross features of the brain but do not resolve its structure well. structural MRI allows: - detection of brain damage detection of lesion location measurement of lesion extent detection of damage to connections

CT scan - computed tomography

An imaging method that uses a modified MRI scanner reveal bundles of axons in the living brain. we can visualise connections in the brain

DTI - diffusion tensor imaging

His experiment involved passing an electrical current through one coil and measuring the effect in an adjacent coil The effect in the adjacent coil was present only when magnetic field was changing (switching on/off) This was the first demonstration of magnetic induction the entire basis of TMS Must switch on and off to get electromagnetic induction.

Faradays coil

So from millisecond to a day 1) single cell and microstimulation 2) MEG, ERP, TMS, EEG 3)fMRI 4) PET 5) MRI 6) CT

List the brain measures in terms of temporal resolution

So from brain to molecule: 1) EEG ERP MEG 2) CT MRI PET fMRI 3) TMS 4) single cell and microstimulation

List brain measures in terms of spatial resolution

Same side

Ipsilateral

Opposite side

Contralateral

One of 3 membranes that act as protective layers around the spinal chord. the three are: - dura mater: tough flexible outermost meninx - the arachnoid: spider web, middle layer, like sheet of cellophane ---- the subarachnoid space: filled with CSF - pia mater: last layer, adheres to surface of brain

Meninges

- set of hollow chambers within the brain filled with CSF, including two lateral ventricles (containing the choroid plexus). the third and fourth ventricle are connected by cerebral aquaduct

Ventricles

- cerebrospinal fluid - formed by the choroid plexus - circulated in subarachnoid space - reabsorbed in the arachnoid villus or hydrocephalus in an infant.

CSF

Cell bodies

Grey matter

Axons and dendrites wrapped in lipids

White matter

Sylvian fissure

Fissure between frontal and temporal lobe

How functioning is mapped and controlled in the brain in the motor cortex and somatosensory cortex

Somatotopic organisation

A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells. - isn't a systematic mapping system, just numbered by when they appeared from staining. - e.g. primary auditory is 41

Brodmann area

The limbic system is a set of structures in the brain that controls emotion, memories and arousal. It contains regions that detect fear, control bodily functions and perceive sensory information (among other things) within the telencephalon and Includes the: - hippocampus - amygdala - fornix - others components within this limbic region

The limbic system

- a group of structures linked to the thalamus in the base of the brain and involved in coordination of movement. - within the telencephalon and involves a number of subcortical nuclei. - includes the caudate nucleuis, putamen, globus pallidus

Basal ganglia

- thalamus and hypothalamus

Diencephalon

- mesencephalon: tectum and tegmentum

Mid brain

Rhombencephalon: cerebellum, pons and medulla oblongata

Hindbrain

- white matter is outer surface - grey matter is inner section - dorsal roots - sensory and afferent - ventral roots - motor and efferent

Spinal chord

- somatic is movement of skeletal muscles - includes 12 cranial nerves attached to ventral surface of brain e.g. nerve 10 is vagus nerve - includes 31 pairs of afferent and efferent spinal nerves

Discuss somatic control within the peripheral nervous system

- autonomic functioning keeps us alive i.e. vegative functions - smooth muscle, cardiac muscle, glands - sympathetic and parasympathetic - all nerves are efferent

Discuss autonomic control within the peripheral nervous system

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