Human Cognition Chapter 2

Understanding the brain through Capgras syndrome

Common understanding is that regions are strictly responsible for specific functions but is this really the full story? Consider Capgras Syndrome

Capgras Syndrome

Patients can recognize their loved ones, but they believe that they are imposters. Think the real loved one was kidnapped (or worst). May even see slight “defects” in the '“imposter”. Normal face recognition involves two systems: Cognitive appraisal and Emotional appraisal. In __, emotional processing is distrupted

Cognition Appraisal

This person looks like my dad

Emotional Appraisal

This person feels like my dad

Capgras Syndrome-Whats damaged

Amygdala damage results in a lack of emotional response. prefrontal cortex damage impairs reasoning. Can lead to confidence in illogical thoughts. “the simplest explanation is probably the truth”. More intricate explanations aren’t dismissed without intact prefrontal cortex (eg, this person looks exactly like my dad, but something doesnt’t)

What can we learn from Capgras Syndrome

Capgras Syndrome is a rare psychoatric disorder where a person believes that familiar people (like family members) or places have been replaced by identical imposters

Recognition involves separate mechanisms

Factual knowledge. Emotional knowledge and reactions

Factual knowledge

This is knowing who someone is based on facts, like their name or relationship to you

Emotional knowledge and reactions

This involves the feelings and emotional responses you associate with that person. The amygdala plays a key role here, processing emotions and Linking them to memories

Amygdala linked to emotional processing

Feelings of familiarity, memory for emotional events, and emotional decision making. Even “simple” processing In the brain involves multiple regions

Feelings of familiarity

This is that gut feeling you get that tells you, you know someone or something

Memory for emotional events

Our memories are often stronger and more vivid when they have an emotional component

Emotional decision making

Our emotions can influence the choices we make

Capgras Syndrome deepdive

It’s thought that there might be a disconnect between the factual knowledge of someone’s identity and the emotional response or feelings of familiarity that normally accompanies recognizing them. So, the person knows intellectually that it’s their spouse, but they don’t feel the familiar emotional connection, leading them to believe it’s an imposter. Even seemingly simple processes like recognition are complex and involve many brain areas working together

Structures of the brain

We can’t talk about Cognition without a basic understanding of the brain. Left cerebral hemisphere, structures on the right are similar, but don’t always have the same functions

It’s the Hindbrain, midbrain and the forebrain

The Hindbrain

(Cerebellum, pons and medulla). Top of the spinal cord.

Key life functions-Heartbeat and breaking rhythms, posture and balance, and alertness

Cerebellum

Also responsible for movement, spaital reasoning, sound discrimination and sensory integration

The midbrain

Coordinates movement (especially eye movements), auditory pathways from ears to forebrain, and regulates pain experiences

The forebrain

Responsible for most of cognitive experience, surrounds the midbrain and most of the hindbrain, outer surface=the cortex (3mm thick, 80% of the brain), divided into two hemispheres by the longitudinal fissure, and consists of four lobes and a variety of subcortical structures.

Also includes thalamus, hypothalamus and limbic system (amgydala and hippocampus)

Thalamus

Sesnory relay station

Hypthalamus

Simple motivated behaviours (eating, drinking, sex)

Limbic system

Has the amygdala and hippocampus

Structures of the brain-lateralization

Cortical organization is ___

The left side of the body and perceptual world has more representation on the right side of the brain, and vice versa

Severed Corpus collosum=”split brain” patients

When a split-brain patient is asked what he sees, the left hemisphere sees the fork on the right side of the screen and can verbalize that

Left hemisphere

Produces language

Right hemisphere

Sees the spoon on the screen’s left side, but it cannot verbalize that. However, if the patient reaches with his left hand to pick up the object, he does select the spoon

Spatial judgement. Can only point, no langauge

The corpus collosum

Connects the two sides of the brain; cutting it stops them from talking to each other, so the left side can’t name what the right side sees

Example of Severed corpus callosum

If a patient is shown a picture of a spoon in their left visual field, the right side of the brain sees it but cannot name it because the speech center is on the left. If asked what they saw, they would say “nothing”, yet they could still use their left hand to pick out a spoon from a hidden pile of objects

Sources of evidence about the brain

How can we learn information about the brain? We gain valuable information from brain damage patients, but we also rely on other methods for experimentation

Neuroimaging methods

Transcranial magnetic stimulation

Magnetic Resonance Imaging (MRI)
Functioning Magnetic Resonance Imaging (fMRI)

Electroencephalography (EEG)-event related potentials

Transcranial Magnetic Stimulation

Magnetic fields carry an electrical pulse into the brain to stimulate neurons

Cerebral Cortex

The outer layer of neural tissue of the cerebrum, responsible for high-level processes like memory, attention, perception, Cognition, awareness, thought, language and consciousness

Capgras syndrome is linked to the cerebral cortex

because it involves a disconnection between the visual recognition areas in the temporal lobe and the emotional processing centers in the limbic system. While split-brain involves the corpus callosum, Capgras syndrome specifically highlights how the cortex fails to integrate sensory input with emotional responses, leading to the belief that familiar people are imposters

Both conditions involve the cerebral context, but they highlight different types of connectivity failures

Lateralization

The division of labour between the two brain hemispheres, where specific cognitive functions are localized primarily to one side; for example, language processing is typically dominant in the left hemisphere for most people, while spatial reasoning and facial recognition are often more active in the night

Lateralizaiton and split brain

Lateralization is the reason split-brain surgery has such distinct effects, as cutting the corpus callosum forces these specialized hemispheres to operate in isolation, while the cortex relies on these specialized regions to integrate complex information like visual identity and emotional meaning

Cognitive Psychology Methods

Employs experimental methods like reaction time measurement, accuracy tracking, and eye-tracking to infer mental processes, alongside neuroimaging techinques such as fMRI and EEG to map these behaviours to specific cortical activity

Cortical activity

The electrical firing of neurons in the brian’s outer layer, which researchers track to observe how the brain processes information, performs tasks, or experiences the functional deficits seen in conditions like split-brain or capgras syndrome

Functional magnetic resonance imaging (fMRI)

Detects changing in blood flow to identify active brain regions, allowing researchers to visualize which parts of the cortex are engaged during specific cognitive tasks

Electroencephalography (EEG)

Uses sensors on the scalp to measure electrical activity from neuronal firing, providing high temporal resolution to track the exact millisecond-by-millisecond timing of brain reponses

Amgydala

Emotional processing

Hippocampus

Learning and memory