Biopsychology Flashcards
central nervous system
comprises of the brain and spinal cord and has two functions: control behaviour and regulate the body’s physiological processes
the brain
-Receives information from the sensory receptors
-Responsible for coordinating sensation, intellectual and nervous activity
-Sends signals to the muscles and glands of the body
the spinal cord
-Bundle of nerve fibres enclosed within the spinal column
-Main function is to relay information between the brain and the rest of the body
-Also contains circuits of nerve cells that allow us to perform simple reflex actions eg. pulling hand away from something hot
PNS
the nerves outside of the brain and spinal cord, that connect to the CNS.
⤷The peripheral nervous system has two branches - the somatic and autonomic nervous systems.
⤷The autonomic nervous system controls involuntary, vital functions of the body, which can be further split into 2 branches.
⤷The somatic nervous system receives transmits and receives information from the senses and direct muscles to react and move (voluntary movements).
endocrine system
⤷Consists of glands that release hormones into the bloodstream
⤷Pituitary gland = master gland
⤷Other important glands = adrenal glands, ovaries, testes
hypothalamus
controls the pituitary gland
⤷The hypothalamus receives information from many sources around the body and responds when the body deviates from normal conditions.
⤷One of the ways it does this is by regulating the hormones produced by the pituitary gland.
pituitary gland
produces hormones.
⤷Some of these hormones directly bring about physiological reactions in cells, others cause other glands to produce hormones
negative feedback
High levels of a pituitary hormone in blood
Receptors in the hypothalamus detect the high levels
Pituitary gland stops releasing hormones
sensory neurons
carry impulses from sensory receptors to the CNS. when impulses from sensory neurons reach the brain they are translated into sensations so the organism can react appropriately
relay neurons
connects sensory and motor neurons found in the CNS
motor neurons
found in CNS, connected to the muscles or glands and bring about responses
relay action
⤷Automatic, rapid responses that do not involve conscious areas of the brain.
⤷Consist of just three neurons.
⤷Protective responses that occur in response to certain stimuli.
synaptic transmission
⤷Action potential reaches the the synaptic knob and causes vesicles containing neurotransmitter to move towards presynaptic membrane.
⤷Vesicles fuse with presynaptic membrane and release neurotransmitter into the synaptic cleft.
⤷Neurotransmitter diffuses across cleft and binds to receptors on postsynaptic membrane.
⤷The binding causes an action potential in the postsynaptic neuron
excitatory
Involves a neurotransmitter than upon binding to the receptors increases the likelihood of an action potential occurring in the postsynaptic neuron. (EPSP - Excitatory postsynaptic potential)
inhibitory
Involves a neurotransmitter that upon binding to the receptors decreases the likelihood of an action potential occurring in the postsynaptic neuron. (IPSP - Inhibitory postsynaptic potential)
acute stress
⤷Amygdala sends stress signals to the hypothalamus
⤷Hypothalamus activates sympathetic nervous system
⤷Sympathetic nervous system causes the adrenal medulla to release adrenaline
⤷When threat has passed parasympathetic nervous system becomes active and reduces adrenaline release
adrenaline
⤷Increased heart beat (increases blood flow to organs)
⤷Breathing rate increases (increased oxygen intake)
⤷Triggers release of glucose and fats (more energy release)
chronic stress
HPA Axis (Hypothalamic-pituitary-adrenal axis)
⤷Hypothalamus releases corticotrophin-releasing hormone (CRH)
⤷CRH causes anterior pituitary to release adrenocorticotrophic hormone (ACTH)
⤷ACTH causes the adrenal cortex to release cortisol`
end-and-befriend response
⤷Women respond to stress by tending to offspring and befriending other women - Taylor et al (2000).
⤷Women have higher levels of oxytocin that could be responsible for this.
⤷SRY gene on Y chromosome is responsible for promoting aggression and resulting in a fight or flight response.
⤷Von Dawans et al (2012) challenge the argument that only women exhibit the tend and befriend response.
⤷Human connections are formed between men and women during crisis (9/11)
fight or flights evaluations
-poor real world validity (Everyday stressful situations dont regularly need you for fight or flight.Can cause strain on your heart if stress is constant)
-external validity (Freeze response.Meaning you are hypovigilant to danger)
-low population validity
localisation of function
Simple organisms don’t have the nervous system divided
Complex organisms evolved specialised nerves and connections for important tasks - resistant to damage
Functions are associated with activity in specific areas
motor cortex
stimulates and controls conscious physical movements
somatosensory
Synthesises sensory information from the peripheral neurons to create physical sensations
visual cortex
Has 5 layers, orients stimuli, depth perception, shapes
auditory cortex
Receives signals from the ears and creates auditory perceptions (hearings)
brocas area
centre for language production, combines essential signals from other regions to create speech
wernickes area
Centre for making sense of language - interprets physical and verbal communication
localisation of functions evaluations
-reliable and valid (Stroke patients show aphasia - specific functions were lost when damaged in corresponding brain areas.Stroke patients have uncontrolled brain damage - ungeneralizable to most people)
-evolutionary benefits (localised function helps survival - individuals can still function even if they suffer some brain damage.Localised specialist brain areas allow greater flexibility + intelligence - others free for other tasks)
-generalisability ( Localisation decreases with age - as we get older more neural connections are strengthened - “plasticity”, old = less localised. Male brains are more localised than female brains which are more functionally integrated on average)
lateralisation
There are two different halves to the brain
Both hemispheres communicate via the Corpus callosum
Some functions are mirrored in both hemispheres while others are just localised in only one hemisphere
sperry
Aim: investigate hemispheric lateralisation of function in split brain patients
IV1: number shown to right hand side
IV2: number shown to left hand side
DV(a): accuracy in reporting stimuli via hand signal
DV(b): accuracy in reporting numbers via speech
Findings:
Stimuli shown to rhs can be presented by language but not not hand signal
Stimuli shown to lhs can be presented by hand signal but not language
Conclusion:Severing the corpus callosum in the brain prevents lateralized functional areas from receiving signals from the opposite side of the brain
Functional areas localised on both sides of the hemispheres will always connect to the opposite side of the body - Contralateral Organisation
plasticity and function recovery
Plasticity - The ability to change and adapt in response to experience
Humans are born with small and incomplete brains and make new neural connections through their life
Connections develop fastest at a young age ( young minds are more plastic and willing to change)
Unused pathways are destroyed - Pruning
Plasticity can help recovery from injury
Structural Plasticity (growth) - Experience causes a change to brain structure
Functional Plasticity (recovery) - When localised functioning tissue of the brain is damaged - the localised functioning moves and occurs in a different area of the brain that is undamaged
neuroplastic growth
Synaptic Pruning - unused axons are weakened and then destroyed
Neural Unmasking - Hormone, growth factor called NGF is released by overused neuron to encourage growth
Axonal Sprouting - “guidance proteins” and neurotrophins encourage growth
Synaptic Connections - New connections form and strengthen an ‘overused’ neuron so it can cope with more usage
Neuroplasticity functional recovery
Axon Damage (Axotomy) - Axon is severed due to injury
Axonal Sprouting - New axon / dendrites grow toward the target area as it releases NGF (growth factor)
Blood vessels reform (capillary + glial cells) - “glial cells” wrap around capillaries; support blood-brain barrier)
Recruitment of homologous (similar) areas - usually on opposite hemispheres
fMRI
Ppt performs task inside electromagnet tunnel
Magnetic field nuclei aligns hydrogen nuclei
Radio pulse “flips” nuclei, when they re-align, they release energy
Energy differences are mapped using a coil onto a computer generated frame - brighter areas signify more blood flow - more usage
Strengths: non-invasive, objective, reliable, better than self report, no radiation
Weaknesses: Correlational as it suggest blood flow = activity, shows working regions but no neural connections (connectome project)
EEG
Measures electrical activity in the brain using scalp connections and can diagnose epilepsy (spikes) and Alzheimer (less activation)
EEGs detect 4 types of waves:
Gamma (alert/problem solving/learning), Beta (awake and aroused), Alpha (awake + relaxed), Theta (Light sleep /dreaming/ deep meditation), Delta
Strengths: cheap, observe changes in frequencies of brain waves,
Weaknesses:Neocortical measurements only (surface level only), Correlation of wave frequencies
ERPs
Initially repeat experiment many times to find a baseline for brain voltage
Infer electrical activity caused due to the activity
Sensory ERP - within 100 ms of stimuli
Cognitive ERP - after 100 ms of stimuli
Strengths: cheap, strong application, law enforcement / used as lie detector
Weaknesses: Correlational (third variables), large number of trials needed for base - time consuming, neocortical measurements only
post mortem
Inspection of individuals brain known to have an impairment after their death to find what went wrong with their brain
Strengths: Highly detailed, all regions available, strong applications in understanding medical research
Weaknesses: Correlational only and can’t be tested, lots of confounding variables (and extraneous variables)
circadian rhythms
A biological rhythm - a repeating pattern in behaviour in a body’s system
Evolutionary pressure on these rhythms include avoiding predators and repair/growth/recovery
Biological clock responds to sunlight
24-hours light-dark cycle
Each morning - light stimulates intrinsically photosensitive retinal ganglion cells to transmit a signal to the Suprachiasmatic Nucleus
This signal travels to the suprachiasmatic nucleus in the hypothalamus through the Retinohypothalamic Tract
Suprachiasmatic Nucleus transmits signals of neuroendocrine and autonomic descent to synchronise rhythm in all tissue
As light levels decrease, the pineal gland begins to secrete more melatonin which nullifies the signals from the SCN - leads to sleep
example of circadian rhythm
7:30am - Melatonin secretion stops
2:30pm - Best coordination
5:00pm - Greatest cardiovascular efficiency + Muscular strength
9:00pm - Melatonin secretion starts
ultradian and infradian rhythms
7:30am - Melatonin secretion stops
2:30pm - Best coordination
5:00pm - Greatest cardiovascular efficiency + Muscular strength
9:00pm - Melatonin secretion starts
INF the menstrual cycle
Menstruation (uterus lining sheds) →
Ovulation (mature egg released from ovaries) →
Uterus lining thickens more →
Menstruation + repeats
seasonal affective disorder
overreacting, unexplained weight gain, Depression, sleeping more
Summer SAD = loss of appetite, unexpected weight loss, Insomnia, irritability
The glymphatic system
Cerebrospinal fluid helps remove waste products of the brain in a convection process
Happens in pulses, faster at night than at day
Can be applied to help understand Alzheimars disease → may develop treatments
endogeous pacemaker
Internal stimuli that control biological rhythms (e.g. suprachiasmatic nucleus, pineal gland)
suprachiasmatic nucleus
“Master circadian clock” - controls cycles in other organs
Researchers took hamsters with two different circadian rhythms and implanted their SCN into one another. In all cases, the donors circadian rhythm was followed
Pineal Gland
Receives signals from the SCN, depending on light levels to produce melatonin
Melatonin is derived from serotonin and is inhibitory. It can inhibit many areas of the brain such as the ones responsible for wakefulness (mesencephalon, limbic system)
→ leads to sleep
exogenous zeitgebers
External stimuli that control biological rhythms and processes (e.g. light)
Light
Rods and cone cells in eyes use opsins to detect light
Third photoreceptor cell: ipRGCs (Intrinsically photoreceptive retinal ganglion cells)
ipRGCs use melanopsin to detect and communicate intensity of light and the wavelength
