COG PSYCH 2

• Patients can recognize loved ones, but think that they’re actually imposters.

  • Under the belief that the real loved one was kidnapped (or worse)

  • May even see slight differences between the real loved one and the “imposter”

  • Eventually leads to paranoia due to believing that ‘someone is lying in plain sight’

• Damage from the brain that can come from diverse backgrounds.

What is Capgras syndrome?

• Cognitive Appraisal

  • Looking at someone and recognizing them from their facial properties.

• Emotional Appraisal

  • Requires hypothalamus and thalamus

  • Trying to tell you how to feel about a certain face

  • * In Capgras syndrome, this part is damaged/disrupted

    • “I’m looking at my [ loved one ], but I feel nothing?”

What are the two systems of normal facial recognition?

• The Amygdala is linked to emotional processing, which is also linked to:

  • Feelings of familiarity

  • Memory for emotional events

  • Emotional decision making

  • A close neighbour to the hippocampus

• Even simple processings in the brain involve multiple regions

  • Data from these different regions must be assembled or connected

What can we learn from Capgras Syndrome?

• Top of the Spinal Cord

• Helps with key life functions

  • Heart rate, breathing, etc

• Cerebellum - the largest region of the hindbrain

• Also includes the pons and medulla

What is the Hindbrain?

• Serves as a hub to boost information from the brain

• Coordinating precise eye movement

  • Rapid small movements to keep sustained tracked movement to an object

• Relaying auditory information from ears to forebrain

• Regulates pain experiences

What is the Midbrain?

• Surrounds the midbrain and most of the hindbrain

• Includes the cortex, lobes, and subcortical structures

  • Cortex - outer surface of the forebrain covered in convolutions, which takes up 80% of the brain

• Divided into two cerebral hemispheres

What is the Forebrain?

• Frontal lobes

• Parietal lobes

• Temporal lobes

• Occipital lobes

Fissures divide the cerebral cortex into each hemisphere into what different lobes?

• Thalamus - sensory relay station

  • Different neurons go to the thalamus and the thalamus helps direct them to the specific brain region

• Hypothalamus - controls behaviours that serve specific biological needs (i.e. eating, body temp, stress, etc.)

  • Manages endocrine system

• Limbic System, two parts:

  • Amygdala - emotional processing

    • The olfactory system is close to this, meaning certain smells could give certain emotions.

  • Hippocampus - learning and memory

    • Relating to the amygdala, it can help recognize and learn if certain things are threatful

What are the Subortical Structures?

• The brain is divided into (roughly) symmetrical left and right hemispheres

  • Contralateral cortical organization

  • Connected by commissures (thick bundles of fibers that carry information)

    • Largest commissure is the corpus callosum

What is Lateralization?

• Both hemispheres are damaged

• Severed corpus callosum

  • Was a last-resort treatment for severe epilepsy

  • Severely limits communication between the hemispheres

• Evidence for some hemispheric specializations of functions

What are Split-brain Patients?

• Using structural neuroimaging techniques

  • Records the ‘structures’ of the brain

    • Blood distribution in general

  • Computerized Axial Tomography (CT) scans

  • Magnetic Resonance Imaging (MRI) scans

    • Uses magnets that ‘shake’ to show the amount of blood in each portion of the brain

• Using functional neuroimaging techniques

  • Records ‘function’ of the brain

    • “Where in the brain is activity taking place?”

    • Where is the blood going when performing a certain task?

  • Position Emission Tomography (PET) scans

What is structural and functional neuroimaging techniques?

• Communication between neurons is chemical

  • Neurons communicate with one another via neurotransmitters

• Communication within a neuron is electrical

  • The input end of a neuron receives neurotransmitters, the output end releases neurotransmitters

  • An electrical impulse conveys the signal from the input end to the output end

How do neurons communicate between and within?

• Recording of the electrical communication within neurons

• It is used to study:

  • Broad rhythms (i.e. sleep stages)

  • Event-related Potentials (ERPs)

What is an EEG? (Electroencephalogram)

• Brain function can also be studied through techniques that manipulate the functions

  • Chemical effects on neurotransmitters

    • EX) Depression medications. Allows serotonin reuptake.

    • EX) Taking pain medications (i.e. acetaminophen). Inhibiting certain pain receptors.

  • Electrical stimulation

  • Gene manipulation

• Ethical considerations

  • Institutional review boards

How can we manipulate certain brain function?

• EEG:

  • S: temporally locating neural activity (when?)

  • W: spatially locating neural activity (where?)

• fMRI:

  • S: spatially locating neural activity (where?)

  • W: temporally locating neural activity (when?)

• MRI scans:

  • Detecting brain structures but NOT activity

What are the strengths and weaknesses of an EEG, fMRI, and an MRI?

By combining techniques.

In the previous method, how can we limit the weaknesses?

Most neuroimaging techniques used to study brain activity and structures provide only correlational data, meaning no causality can be determined

• That said, what are the sources of causal data?

  • Brain lesions

  • Transcranial Magnetic Stimulation (TMS)

    • Produces magnetic pulses that activate neurons

    • But also creates temporary lesions, to ‘take specific parts out of the game’

    • Deep TMS

    • Conventional TMS

      • Creates functional lesions for a period of time

  • Transcranial Direct Current Stimulation (TDCS)

What is the problem with neuroimaging techniques? How is it solved?

• Largest portion of the human brain

• A thin layer of tissue covering the cerebrum (i.e. forebrain)

• Regions of the cortex

What is the cerebral cortex?

• Primary sensory projection areas - arrival points in the motor cortex for signals from the sensory 

• Primary motor projection areas - departure points in the motor cortex for signals that control muscle movement

• Contralateral Control

• More cortical coverage reflects greater motor precision

What are the motor areas of the cerebral cortex?

• Somatosensory Area - skin sensations

• Primary Auditory Cortex - auditory sensations

• Primary Visual Cortex - visual sensations

  • Contralateral organization

  • Cortical space assigned based on acuity

What are the sensory areas of the cerebral cortex?

• Contains many specialized subregions, damage to which can result in:

  • Apraxia - brain struggles to plan and sequence physical movements

  • Agnosia - loss of recognition of familiar objects, smells, people, shapes, sounds, etc., despite having intact senses

  • Unilateral Neglect Syndrome

  • Aphasia

What can happen to the many specialized subregions of the cerebral cortex?

• Dendrites - detects incoming signals from other neurons

• Cell Body - contains the nucleus and cellular machinery

• Axon - transmits signals to other neurons

What are the basic parts of a neuron?

• Guides development of the nervous system

• Repairs damage in the nervous system

• Controls nutrient flow to neurons

• Electrical insulation

What are glias?

• When a neuron receives a message:

  • A neuron is stimulated and is either ready to fire or it doesn’t (all-or-nothing)

• Neurotransmitters change the postsynaptic membrane

  • If there is sufficient ionic flow to surpass the cell’s threshold, an action potential is produced

• More than 100 neurotransmitters have been identified so far

What are synapses?

• Allows a neuron to receive and integrate information from many other neurons

• Neurons can compare incoming signals and adjust responses to input as per other incoming signals

• Strengths of synaptic connections are adjustable:

  • They are altered by experience

  • Considered crucial for learning

What is synaptic transmission?

• How is information represented (or coded) by neurons?

  • Specific neurons can, in some cases, represent specific stimuli

  • “Pattern coding” or distributed representation

    • More complex movements (i.e. which parts of the brain are activating to activate specific muscle regions and what not?)

What is Coding?