PSYCH 2NF3 midterm

hypothesis

• an educated guess about the way something functions

• “educated” because we base hypotheses off our previous experiences and knowledge

• once you have a hypothesis the next step is to create an experiment

  • i.e, engage in hypothesis testing

the blob

• Before we had a clear understanding of how things function in the body, we had a 'blob'

• People who looked at the body observed a blob of tissue at the top of the head

• They hypothesized the purpose of the tissue (not only in the brain, but all over the body)

What was Daniel M Wolpert’s hypothesis?

we have brains to produce adaptable and complex movements

What was the evidence Daniel M Wolpert used to support his hypothesis?

• movement is the only way to produce change in the environment

• cognitive functions only exist to drive future movements

• an underwater creature known as the sea squirt digests it’s own brain and nervous system when it becomes stationary in adulthood

significant historical perspectives on the mind and brain

• Aristotle

• Galen

• Renes Descartes

• Phrenologists

significant historical perspectives on the mind and brain → aristotle

• his theory was connected to mentalism

• proposed that a non-material psyche is responsible for human thoughts, perceptions, and emotions, and this psyche works through the heart to produce action

• developed the cardiac hypothesis

mentalism

the idea that we have a mind and it governs our behavior and makes one person different from another

the cardiac hypothesis

• the notion that the mind resides in the heart

• created by aristotle

• came from understandings of feelings and where they can be percieved in the body

significant historical perspectives on the mind and brain → galen

• galen (a physician who worked with gladiators) was interested in documenting how different organs function

• he observed that we have connections from the bottom of our foot to the top of our head

• this inspired him to develop the brain hypothesis

the brain hypothesis

• the hypothesis that the entire body is connected to a blob of tissue at the top of the body, so the mind resides in the brain

• created by galen

significant historical perspectives on the mind and brain → descartes

• proposed the dualism perspective

  • physicists at the time disputed the dualistic way of thinking and proposed “the mind-body problem”

• stated that the mind is located in the brain

Dualism - Descartes

• the mind is a non-physical entity within the brain, which is a physical entity

• connected to the “mind-body problem,” was people wonder how something non-physical can govern something physical

the phrenologists

• the phrenologists were a group of individuals interested in mapping out areas of the brain

• they proposed that we had unique parts of the brain that mediated specific areas of behavior

• believed they could map out brain activity by feeling peoples skulls

• Were not taken very seriously because they performed clinical practice using this model

• led people to start thinking of the brain as something that has components

What is our current understanding of the relationship between the mind and behavior?

• materialism → the idea that all behaviour can be fully explained by the workings of the central nervous system

• rooted in evolutionary theories

case studies

• the in-depth investigation into a single person or group

• responsible for the development of neuropsychology as a feild

• became the standard for studying brain function before technology

gyri

the folds of the brain

sulci

• dips in the brain

• big sulci are known as fissures (such as the longitudinal fissure

what is the correct name for the green? what is the correct name for the red?

the red = gyri, the green = sulci

Broca’s area

• discovered by and named after paul broca

• located in the frontal lobe of the left hemisphere

• associated with the motor movements used in speech

• was interpreted as an example of strict functional localization

Broca’s aphasia

• caused by damage to Broca’s area

• a language disturbance characterized by motor problems; individuals struggle to get the words out and speak fluently

• typically not accompanied by a loss of understanding

• speech is limited to short utterances

• producing the right sounds/words is a laborious process

if this image depicts the left hemisphere of the brain, what is the highlighted blue area and what is the highlighted brown area

• the blue = broca’s area, located in the left frontal hemisphere

• the brown = wernicke’s area, located in the left temporal cortex

Wernicke’s area

• discovered and named after Carl Wernicke

• located in the left temporal cortex

• associated with the organization of words and speech

• discovery used as evidence against strict localization

Wernicke’s aphasia

• a language disturbance involving the organization of speech

• speech production occurs but words often make no sense

  • patients may include non-existent or irrelevant words in speech

• usually results in profound comprehension deficits

• are unaware that their own speech doesn’t make sense

Wernicke’s model of speech

• Describes the brain as a circuit & states that there's a 5 step sequence in which information moves in the brain

• Argues against the idea of strict localization

• Implies theres a motor pathway connected to both Wernicke's & Broca's areas

Wernicke's Model Process

1. Sound sensations enter the brain via the auditory pathway
2. Sound representations are stored & processed in Wernicke's area
3. Information is sent to Broca's area through the acuate fasciculus
4. In Broca’s area, sound representations are converted into representations of speech movement
5. Speech movements are sent to the motor pathway for articulation

what is a ‘pathway’?

a bundle of neurons travelling together in the same direction

what is aphasia?

• an acquired communication disorder

• ACQUIRED because it happens later in life

the brain mappers

• a group of individuals who were interested in labelling parts of the brain

• using cytoarchitectonics (stamping) korbinian brodmann revealed there were 6 layers of the brain (distinguished by size, shape, and densities of neurons)

  • the introduction of neuromiaging techniques made his work even more popular

• wilder penfield created the sensory homonculus through his works with cortical mapping

the montreal procedure

• an epilepsy treatment developed by wilder penfeild

• patients are given an anesthesia and are kept awake during open brain surgery

• he would stimulate parts of the brain to track different sensations to identify and remove the area causing seizures

• he was able to create cortical stimulation maps

neuropsychology

• the study of the connection between human behavior and the brain

• informed by two hypotheses:

  • the brain hypothesis

  • the neuron hypothesis

the brain hypothesis

the idea that the brain is the source of behavior

the neuron hypothesis

a major unit of brain structure and function is the neuron (Nerve cell)

patient H.M case study → background

• During the time of brain mapping, patient H.M gained significant attention from neuropsychologists

• H.M (or henry molaison) was walking through the park and got knocked down by a bicyclist, injuring his head

• after his accident, he began experiencing seizures

• his seizures became so bad and frequent in adulthood he was deeply epileptic

epilepsy

• an unexpected electrical activity in a specific area of the brain

• typically occur in the temporal cortex

patient H.M case study → procedure

• to deal with his seizures, H.M decided to have a lobotomy of his temporal lobe to receive the area of his brain causing the frequent seizures

  • at the time, this was a common treatment for seizures

patient H.M case study → outcome of procedure

• As a product of his surgery, he lost the ability to create new memories and had problems with his short term memory

• His long-term memory was unaffected and he could access memories from his childhood

• His story helped develop “the binding problem”

the binding problem

• Memory has multiple different components (short-term, sensory, long-term)

• Concerned with how the brain seamlessly creates meaningful comprehension of experiences

the ventral stream

• the what pathway

• mediates action controlled by conscious visual perception

• damage results in visual agnosia

visual form agnosia

• the inability to recognize objects visually

• with visual form agnosia items can be differentiated by touch

the dorsal stream

• the where pathway

• mediates action controlled by unconscious visual perception

• ex: indivividuals can identify objects but have trouble aiming hands to pick up objects

what are the three portions of a neuron?

• The core region of a neuron is is the cell body

• The branching extensions are the dendrites

  • There is many dendrites

• The main "root" is the axon

  • There is only one axon

what are the two types of cells found in the nervous system?

• the neurons

• the glia

localization of function

the idea that specific areas of the brain control each type of behaviour

lateralization of function

the idea that one specific hemisphere of the brain controls a function not shared by the other

given the history of neuropsychology, what are some key insights from brain injury case studies?

• neuroplasicity → studies on cats with removed areas of the brain found that the passage of time allowed the brain to rewire and function normally

• the brain has a hierarchal organization

• our brain can be cut into two brains by cutting the corpus callosum and smaller comissures

• we have both conscious and unconscious neural streams

what are the four types of brain damage?

• traumatic brain injury

• tumours

• multiple sclerosis

• bacterial infections

traumatic brain injury

• damage or injury to the brain caused by an external force our trauma

• a disruption in the brain that occurs after birth → it isn’t hereditary, congenital, degenerative, or induced by birth trauma

• differentiated in two ways:

  • open head injuries

  • close head injuries

traumatic brain injury → open head injuries

involves penetration of the skull

traumatic brain injury → close head injuries

concussions

concussions

• movement of the brain in the skull

• can’t be seen on routine x-rays, CT scans, or MRI’s

• affects the way a person may think

• can cause a variety of symptoms

concussions → coups vs countercoups

• a coup is the site of the blow

a countercoup is the possible brain damage caused by compression of the side of the skull opposite to the coup

• a severe coup or countercoup may be accompanied by bleeding or a subdural hematoma

  

in a concussion, what is the blue arrow pointing to and what is the red arrow pointing to?

• the blue arrow is pointing to the coup, the point of impact on the skull

• the red arrow is pointing to the countercoup, an area where brain damage can occur opposite side to the site of a blow

Dementia Puglistica (Boxer’s Syndrome)

• another name for chronic traumatic encephalopathy (CTE)

• a degenerative brain disease thought to be caused by repetitive head trauma

• commonly experienced by athletes ** but can occur in anyone

• the repeated head trauma is thought to scar brain tissues

• considered a “dementia” because there is memory and motor related brain disturbances

Dementia Puglistica → symptoms

• Progressively declining cognitive ability

• Short-term memory loss

• Tremors

• Loss of coordination

• Difficulty in speech

• Changes in gait

• Emotional disturbances

Dementia Puglistica → case study on p-tau

• a patient who died very suddenly was a retired professional boxer

• his brain scan revealed an accumulation of p-tau proteins in the neurons and glial cells

Tau proteins

• Help stabilize microtubules in the brain

• Super important for the transportation of nutrients & other molecules within nerve cells

• They lose their ability to stabilize microtubules when phosphorylated & instead clump together

P-tau

• phosphorylated tau proteins

• important markers of brain injury & disease

• found in abnormal deposits in the brains of individuals with Boxer's syndrome

• believed to contribute to the degeneration of brain cells & the development of cognitive & behavioural symptoms associated with the condition

what E4 variant puts athletes at a higher risk of developing brain injuries?

APOE; it helps the body repair from injury

concussions and prolonged rest

• studies have shown that prolonged rest is not necessary after experiencing a concussions

• after an initial day or two of rest, a concussed person should try to go about daily life until symptoms become too difficult

• sitting around thinking about symptoms can make them seem worse and people adopt a sick role psychologically

why are some concussions more difficult to recover from?

• axonal health

  • axons are insulated by fat and if the axons are damaged, it can impact how fast electrical signals are sent leading to delayed reaction times

• mental health

  • ex: post-injury anxiety

concussions → stats canada data and GBA+

• concussions in sport are recognized as a public health issue because of their frequency and potential for long-term consequences

• previous dats suggests that concussions happen more often in young people; specifically males

• however, after a gender based analysis (GBA+), children of both sexes had similar concussion rates until adolescence, when females increasingly experienced more concussions

• females have been found to experience more symptoms, worse reaction times, and greater cognitive decline than males from concussions

tumours

• an abnormal growth of cells

• diagnosed through imaging (which is crucial for establishing a correct diagnosis)

• there are two different categories of tumours:

  • malignant tumours

  • benging tumours

• which can further be classified as gliomas or meningiomas

• symptoms → pressure in skull and disruptions related to location

categories of tumours

• malignant

• benign

categories of tumours → malignant

• Lack distinct boundaries; can move around areas of the brain

• Likely to recur following surgical removal

• Travel through metastasis

Metastasis

the process in which malignant tumours shed their cells and travel to other cites

categories of tumours → benign

tumours contained within their own membrane

types of tumours → gliomas

tumours that develop in the glial cells

types of tumours → meningiomas

• tumours that grow out of the meninges

• close to the surface of the brain so they are easy to remove

• typically benign

grading of tumours as outlined by the WHO

• I: benign, slow-growing, responds well to surgery

• II: malignant, slow-growing, increased likelihood of recurrence

• III: malignant, increased likelihood of recurrence and requires aggressive treatment

• IV: rapidly fatal

factors influencing treatment options for tumours

• The type, size, and grade of the tumor

• Whether the brain tumor is putting pressure on vital parts of the brain

• If the tumor has spread to other parts of the body

• The possible side effects that have emerged

• The patient's preferences and overall health

types of treatment for tumours

• surgery

• radiation therapy:

  • high radiation to target and destroy cancer cells

  • can be delivered internally or externally

• chemotherapy:

  • medications that can be given orally

  • works by targeting and destroying rapidly dividing ccells

• targeted therapy:

  • involves using drugs specifically designed to interfere with specific molecules that contribute to the growth and survival of cancer cells

  • minimizes damage to normal cells (which are affected in other treatment methods)

multiple sclerosis

• a chronic autoimmune disease that creates scarring in the white matter of the brain and spinal cord (CNS)

• caused by the immune system mistakenly attacking the myelin on neurons

• leads to inflammation, damage, & disruption of nerve signals

specific complications with multiple sclerosis

• Damages oligodendrocytes (the glial cells that form the myelin on CNS axons)

• Leads to the demyelination of axons

• Affects white matter in different locations

population distribution of multiple sclerosis

• first appears in young adults between the ages of 20-40

• there is modest heritability and environmental factors

• it is 2x more common in those assigned female at birth compared to males

  • theories explaining this finding include hormonal factors, genetic factors, immune system differences between men and women, and lower vitamin D (which is more common in women)

• canada is among contries with the highest rate of multiple sclerosis in the world

symptoms associated with multiple sclerosis

• Numbness, tingling

• Fatigue

• Muscle spasms

• Walking difficulties

• Pain

what is an example of a viral infection that can cause brain injury?

• human immunodeficiency virus or HIV; the virus that causes AIDS

• AIDS can develop into AIDS Dementia Complex

how does HIV turn into AIDS?

• Once you have HIV in your system, if it is detected early enough, individuals can take medications to keep the viral load low (and be HIV negative)

• However, if it goes untreated, you move from HIV negative to HIV positive

• If you have a low enough white blood cell content and are HIV positive, you can develop Acquired Immune Deficiency Syndrome (AIDS)

Acquired Immune Deficiency Syndrome (AIDS) Dementia Complex

• AIDS ca lead to a collection of neurological symptoms

• initial symptoms include difficulty concentrating, forgetfulness, decreased work productivity, low sex drive, social withdrawl, general apathy, and muscle weakness

  • it is commonly misdiagnosed as depression

• advanced symptoms include severe motor and cognitive disturbances

Acquired Immune Deficiency Syndrome (AIDS) Dementia Complex - Canadian Perspective

• Had a 90-90-90 goal

• Aimed to train healthcare providers to be really vigilant & know what questions to ask to accurately diagnose, treat, & suppress HIV

• In 2016 the process was close but not at the goal yet; the COVID pandemic decreased progress as well

How does HIV work indirectly?

• HIV invades macrophages, microglia, astrocytes, and vascular endothelial cells

• Infected cells release cytokines which results in tissue damage and apoptosis (cell death)

• HIV can bind to special protein structures in the brain resulting the excessive intake of calcium and later neuronal death

Microphages

a type of white blood cell impacted by HIV that destroys microorganisms and dead/dying cells

Microglia

the macrophages of the CNS; impacted by HIV

Astrocytes

the glila cells that provide structural supports to neurons by holding them in place; impacted by HIV

vascular endothelial cells

specific cells impacted by HIV that layer the blood vessels

Important factors in case studies

• past medical history

• family medical history

• general physical exam

• mental health status

blood pressure

• the amount of pressure that your blood is exerting on your artery walls

• measurements of 120/80 are considered normal

how to read blood pressure ratio

• the top number shows how much pressure is exerted when the heart is beating

• the bottom number is a measurement of the pressure between beats

cranial nerves

• the nerves that emerge indirectly from the brain in contrast to the spinal nerves

• numbered in roman numerals from 1-12 from the front of the brain to the back

cranial nerves → olfactory nerve CN1

• Used in smell

• Damage results in the loss of ones sense of smell

• Tested by offering something familiar to the patient and asking them to smell and identify it

cranial nerves → the optic nerve CN2

• used in vision

• damage results in the loss of vision (anopsia)

• Colour blindness is tested with Ishihara plates

• Visual fields are tested by asking the patient to look straight ahead & identify movement in different quadrants of the visual field

• Visual acuity is tested using Snellen charts

Using snellen charts, what does 20/20 vision mean?

The patient sees the same line of letters at 20 feet that a healthy person sees at 20 feet

Using snellen charts, what does 20/40 vision mean?

20/40 vision means that the patient sees at 20 feet what a healthy person sees at 40 feet

fundoscopy

a test that allows diagnosticians to see right into the fundus of the eye

the fundus

• the interior surface of the eye

• includes the retina, optic disc, macula, fovea, and posterior pole

the retina

• Contains specialized cells called photoreceptors

• Responsible for detecting light & converting it into action potentials that the brain can interpret as visual information

the optic disc

• the specific point where the optic nerve exits the eye and connects to the brain

• creates a blind spot because it lacks visual receptors

the macula

• a small, highly specialized area located on the center of the retina

• it is essential for activities that require fine details like reading

the fovea

a region of the highest visual acuity in the eye that is responsible for our sharpest and most detailed vision

the posterior pole

the back portion of the eye; specifically the region encompassing the optic nerve head, macula, and surrounding structures

cranial nerves → the oculomotor nerve CN3

• Used in eye movements

• Tested by examining ones reaction to light, eyelid movement, and deviation of eye outwards

• Damage results in double vision, large pupils, uneven dilation of pupils, and drooping eyelid