Biological Psychology Y11 ATAR

structural organisation of the nervous system

structural organisation of the nervous system

central nervous system and peripheral nervous system

NS function

to maintain the well-being of an organism by regulating internal processes, such as respiration, digestion, heartbeat, and by responding to the external world adaptively through information processing

NS is a

communication system built out of networks of networks which connect the brain, spinal cord, and systems of the body, including sensory receptors, internal organs, and muscles

NS functions by

receiving sensory information, processing that sensory information, initiating and coordinating a response to this information including our muscles, organs, and glands

our response to the environment depends on

past learning and memory

central nervous system consists of

brain and spinal cord

how is the CNS connected to the rest of the body?

through its connection to the peripheral nervous system

CNS function

to receive, process, and respond to sensory information

PNS definition

part of the nervous system that transmits neural messages to and from the CNS, connecting the rest of the body with the cNS

PNS functions

to relay sensory and motor signals, to deliver sensory information to the brain, including information about the body itself and to deliver motor commands to muscles and signals to glands, as part of helping the brain to regulate internal organs

PNS is made up of

all nerves that extend from the brain and spinal cord, that connect with muscles, organs, and glands

somatic NS

part of the PNS that is associated with voluntary control of skeletal muscles and captures external stimuli using sensory organs, and relays information to the cnS

PNS function

to transmit motor commands to muscles as a part of a voluntary response, and sensory neurons receive information from receptor cells

motor neurons connect to

skeletal muscles

autonomic NS

part of PNS that acts largely unconsciously to regulate bodily functions, such as heart rate and digestion

autonomic

self-regulating but requires connection to the brain

ANS function

to allow for automatic non-conscious control of activity levels of internal organs and glands, and to regulate involuntary smooth muscles that control the activity of these organs

how is the ANS a two way street?

it allows the brain to monitor the state of the body and maintain homeostasis by allowing the brain to control the organs and glands of the body

what are the divisions of the ANS?

sympathetic and parasympathetic

sympathetic nervous system

part of the autonomic nervous system that facilitates activation of the flight or fight response as an arousal system

functions of the SYNS

to activate the flight or fight response in emergency situations to help the organism survive

effects of SYNS activation

causes muscle around the adrenal gland to stimulate increased production of adrenaline and noradrenaline

activation leads to more blood, oxygen, energy, and muscle contractions, increase in BP and HR

digestion is stopped, awareness increases

prolonged activation is not healthy

parasympathetic nervous system

division of the ANS that returns the body to a resting state (homestasis) by reversing changes to organs during a sympathetic response, such as rest and digest or feed and breed

is the PSNS slower of faster than the SYNS? why?

slower process, due to noradrenaline and adrenaline taking a while to leave the system and slower neuron pathways compared to the SYNS

sensory neurons

afferent, carry sensory information from receptors

motor neurons

efferent, carry motor information to muscles

dendrite function

receive information from other neurons or the environment

soma function

main part of the neuron that carries out essential functions to keep the neuron alive, integrates and processes information by summing inhibitory and excitatory inputs, and sending a signal through the axon terminal

axon

part of the neuron that transmits an electrical signal to the axon terminal

myelin sheath

a fatty covering of the axon that acts as insulation to prevent the electrical signal from being lost, in turn increasing the speed of the signal

schwann cell

glial cells that form the myelin sheath around axons in the PNS and support the axons to keep them alive

node of ranvier

breaks in the myelin sheath that speed up signal by allowing ions to infuse in and out of the neuron and maintain the action potential as it travels down the axons

axon terminal

the end of the axon that transmits messages to other cells using neurotransmitters at synapses, converting the electrical signal to a chemical equivalent

function of sensory neuron

to send information to the CNS for processing, often from receptors

function of motor neuron

send information from the CNS to effectors (muscles and glands) to be executed

interneurons

send information within the CNS

direction of transmission

the direction of transmission of an electrical, and chemical signal is always from the pre-synaptic neuron to the post-synaptic neuron, due to the fact that there are only vesicles in the presynaptic neuron which are stimulated to release their neurotransmitters into the synapse by calcium ions associated with a neural impulse reaching them

neurotransmitters

chemical signals that cross the synaptic cleft or are used within the nervous system, and they may be excitatory or inhibitory depending on their effects on the potential of the receiving neuron’s dendritic membrane

serotonin

inhibitory transmitter involved in sleep, appetite, mood regulation, low levels associated with mood and sleep disorders

dopamine

transmitter involved with learning, attention, arousal, pleasurable sensation, motivation, and reward, movement as a part of recognising and movement towards reward

parkinson’s disease - loss of dopamine producing cells in substantia nigra

schizophrenia - excess of dopamine

brain

part of NS that receives sensory information, processes it, generates responses, coordinates the body’s organs, and adapts the body’s behaviour to a constantly changing environment

brain parts

hindbrain, midbrain, forebrain

hindbrain

the bottom part of the brain consisting of the brain stem, which connects to the spinal cord

brain stem consists of

medulla, pons, and cerebellum

medulla

regulates vital functions such as heart rate, breathing, blood pressure

if damaged, patient will require life support

cerebellum

bottom part of the brain that appears as a smaller version of the brain, plays a role in coordinating and refining muscle movements, smooth movements, balance, and integrating processed sensory information from the cortex, partially language and attention

midbrain

located either at the top of the brain or is a part of it

relays and filters sensory information to the cortex via the thalamus and contains the reticular formation, plays a role in emotional responses

reticular formation

a wide spread of neurons involved in regulating alertness, arousal, sleep, and attention

reticular formation experiments

affected by anaesthetics

if removed, animals cannot be awoken (cats)

forebrain

the larger, wrinkly part of the brain that is responsible for higher cognitive functions, consisting of the cerebrum, hypothalamus, and thalamus located at the front or upper part of the brain

cerebrum

the upper “wrinkly” part of our brain, consisting of two hemispheres that make up the cerebral cortex

hypothalamus

structure below the thalamus that is connected to the endocrine system

function of hypothalamus

regulates temperature, thirst, hunger, sleep, mood, sex drive, and homeostasis by directing the pituitary gland and the release of hormones (also in ANS as a part of a sympathetic response)

thalamus

a structure in the forebrain that relays sensory information to the cortex like a switchboard (excluding smell)

thalamus abilities

• two way flow of information

• ability to attend particular stimuli

• plays a role in arousal

• switched off during sleep

• damage can lead to blindness and deafness

cerebral cortex

the other layer of the cerebrum that appears as wrinkles, but is only 3 mm deep, consisting of six layers arranged in columns of grey matter

grey matter

cell bodies and unmyelinated axons

white matter

myelinated axons due to white colour of myelin sheaths

where is white matter found?

underneath the cerebral cortex, connecting to various areas of the cortex

contralateral organisation

organisation of the forebrain such that the hemispheres of the brain represent the contralateral side of the body, meaning that the right hemisphere processes the left side, and vice versa.

right hemisphere

• associated with global perspective and perceiving patterns and coherent whole

• non verbal, however necessary for jokes, irony, sarcasm ass they require context

•   associated with spatial skills, facial recognition, map reading, interpreting a picture, and is dominant in detecting and expressing emotion

left hemisphere

associated with language, speaking, reading, writing, understanding language. Analysing information, logical reasoning, focusing on small details, voluntary movement in the right side of body and processes information from the right side of the body (contralateral organisation)

corpus callosum

a wide, thick nerve tract in the middle of the brain consisting of white matter that connects the two brain hemispheres together

frontal lobe function

frontal lobe functions: higher order mental abilities: thinking, planning, problem solving, reasoning, feeling, executive control (controlling impulses and direction attention)

coordinates information, including sensory information, from other lobes, this is done by association areas

responsible for movement via PMC

frontal lobe summary

receives processed sensory and emotional information from the other cortices and limbic system and decides on a response, combining knowledge and emotion to produce movement (action)

damage may lead to

difficulty concentrating, planning, decision making, adapting, following instructions, mood swings, inappropriate behaviour, loss of social cues, apathy, disinhibition, loss of empathy, muscle spasms, loss of fluent, grammatical speech, paralysis

damage to frontal pole

loss of executive functions

damage to orbital lobe

occured to Gage

issues coordinating action and planning with goals and motives

damage to dorso lateral frontal cortex

damage to working memory and problem solving

parietal lobe

The middle upper lobe that processes bodily sensations via the somatosensory cortex, is responsible for spatial awareness, some aspects of speech, has an association cortex involved in reading, writing, solving mathematical problems and integration information from visual and auditory cortices.

damage to parietal lobe

hemineglect

RHS:

loss of imagery and visualisation of spatial relationships

LHS:

effect on math, reading, and writing ability

temporal lobes contain

primary auditory cortex, wernicke’s area (left), limbic system, association areas - play a role in object recognition, memory, and facial recognition

damage to temporal lobes

Damage can lead to loss of auditory processing, loss of memory for objects, faces, and words

occipital lobe

contains visual cortex (that’s it)

broca’s area

area close to the motor cortex in the frontal lobe that controls articulate, clear and fluent speech as well as involved in production and comprehension of grammatical speech

wernicke’s area

Area in the temporal lobe that accesses words stored in memory, enable comprehension of speech and formation of meaningful sentences

Broca’s aphasia

a condition which is a productive aphasia associated with telegram like speech, where speech makes sense but is not fluent and lacks grammatical words

Wernicke’s aphasia

can result in grammatically fluent speech that does not have meaning, and a lack of understanding of spoken speech

primary motor cortex

this cortex is responsible for planning, organising, and sending out motor signals to skeletal muscles, mainly focused on the hands and face because they can be moved the most, also undergoes contralateral control of the body and reception of sensory information

primary somatosensory cortex

cortex that processes bodily sensation with different proportions of sensitivity in each body part, processes touch, temperature, position and pain, has topographical map

primary auditory cortex

processes auditory information, speech in left and non-verbal sounds in right

primary visual cortex

cortex which receives and processes, integrates information from the optic nerves

damage  can lead to blindness even if eyes are intact

achromatopsia

damage to V4 part of visual cortex, colours lose associations

motion blindess

unable to see motion but can see change in position 

projection of PVC

projects to parietal lobe, where partway damage can lead to hemineglect, and projects to temporal lobe, where pathway links shapes and concepts/names, damage can lead to agnosia – shape can be recognised but not identity of object

Phineas Gage

Phineas Gage was a railroad foreman who was involved in accident where a metal rod shot through his head, obliterating a part of his orbital cortex in the parietal lobe

He survived but became more profane, disorganised, and lacked self regulation, planning, and had little social inhibition

Sustained no motor or speech impairments, his memory remained intact

His case was the first to suggest a link between brain damage and personality change

One of the first examples of scientific evidence for the linkage of the frontal lobe to to social inhibition, emotion, behaviours, and characteristics, which led to the development of the idea of localisation of brain lobes and brain structures

Roger Sperry

Roger Sperry studied split brain patients and identified that there were innate, prewired differences between the hemispheres

Right hemisphere – can read, good a special tasks, categorisation based on visual features, geometrical properties, copying designs, reading faces, fitting forms into moulds, recall of non-descript visual forms but is unable to speak

Left hemisphere – responsible for language production

Was also able to identify that the purpose of the corpus callosum was to share information, as each hemisphere seemed unaware of half of the visual and sensory and motor fields

Both hemispheres have a well-developed, seemingly conscious self, similar to the original person

Walter Freeman

Improved the original frontal lobotomy, which was an invasive procedure involving cutting holes in the skull, and instead developed the orbital lobotomy which went through the eye socket and was minimally invasive, quick to do, and easy technique wise

A lot of pressure to come up with a treatment, as asylums in America were overflowing and there were very little viable treatment options for patients

The idea behind the lobotomy was that the limbic system, i.e. the amygdala was over active, and the over activity of the part of the brain responsible for emotions was causing mental illness expressed through behaviour that the frontal lobe produced, so that if the connection between the frontal lobe and limbic systems was severed, the issues would stop

Often used as preventative measures, with children, teens, and overall did about 2500

Effects: trouble regulation emotions, inertia, loss of desire, no speaking, can’t take care of one’s own self, death, paralysis

Some people benefited, others got significantly worse

pre-frontal cortex

part of frontal lobe, contains many other parts to it, eg Broca’s area

responsible for higher order cognitive functions

intelligently regulates our thoughts, actions and emotions through extensive connections with other brain regions

lobotomy damaged this, leading to decreased empathy, short term memory loss, or amnesia

EEG

electroencephalogram

CT

computed tomography

MRI

magnetic resonance imaging

fMRI

functional magnetic resonance imaging

external brain imaging shows

overall brain activity

static imaging

display structures of the brain at a single point in time

dynamic imaging

displays how parts of the brain function over time

EEG function

electrodes are fastened to the scalp to detect and identify electrical activity as a series of peaks and troughs

EEG benefits

good for temporal resolution
good for levels of consciousness

good for sleep and consciousness studies

good for identifying patterns of epilepsy and tumours

whole brain activity

cheap non invasive

EEG limitations

not good for spatial resolution

no images or deep brain activity

CT process

an x-ray beam moves around the body, and abnormal, varying masses or different materials or densities are shown, from this a 3D image is collated from 2D data