PSYB57H3 Chapter Notes - Chapter 2: Capgras Delusion, Ct Scan, Frontal Lobe
Chapter 2: The Neural Basis for Cognition
Capgras Syndrome: An Initial Example
•Capgras syndrome: person is fully able to recognize the people in their world, but is utterly
convinced that these people are not we they appear to be; can accompany Alzheimer’s
•Maybe facial recognition involves two separate systems, one of which involves cognitive
appraisal and one with emotional appraisal; the concordance of the two system leads to
certainty of recognition
The Neural Basis for Capgras Syndrome
•Neuroimaging techniques: developed in the last few decades, allow researchers to take
high-quality, three-dimensional “pictures” of living brains without disturbing the brains’ owners
•Capgras patients have damage in the temporal lobe, particularly on the right side of the head,
in the amygdala: almond-shaped structure that seems to serve as an emotional evaluator,
helping to detect threat or danger.
•Capgras patients also seem to have damage in the right prefrontal cortex: planning, careful
analysis. Has less activity when dreaming, which is why dreams are often bizarre.
The Study of the Brain
•The brain weighs about 3 to 4 pounds
•Size of a small melon
•Contains a trillion nerve cells, ten trillion glial cells
Hindbrain, Midbrain, Forebrain
•Hindbrain: sits directly atop the spinal cord and includes several structures crucial for
controlling key life functions; i.e. heartbeat, breathing rhythm, posture, balance brain’s level of
alertness
•Cerebellum: largest part of hindbrain, coordination of bodily movements, spatial
reasoning, discriminating sounds, integrating the input received from various stimuli
•Midbrain: coordinating movements, precise movement of eyes, relaying auditory information
from ears to forebrain, pain regulation
•Forebrain
•Cortex: outer surface of forebrain, with convolutions: wrinkles
•Longitudinal fissure: deepest groove, running from front of brain to back, separating the
hemispheres
•Frontal lobe: right behind forehead
•Central fissure: divides frontal lobes from parietal lobes: topmost parts
•Bottom edge of frontal lobes are marked by the lateral fissure, and underneath it the
temporal lobes
•Occipital lobes: back of brain, connected to parietal and temporal lobes
Subcortical Structures of the Forebrain
•Subcortical structures: underneath cortex
•Thalamus: acts as a relay station for nearly all the sensory information going to the cortex
•Hypothalamus: controlling motivated behaviours such as eating, drinking and sexual
activity
•Limbic system: surrounding thalamus and hypothalamus. Includes the amygdala and
hippocampus; essential for learning and memory; Figure 2.4
Lateralization
•Commissures: thick bundles of fibres that carry information back and forth between the two
hemispheres, the largest commissure being the corpus callosum
Data From Neuropsychology
•Neuropsychology: study of the brain’s structures and how they relate to brain function
•Clinical neuropsychology: seeks to understand the functioning of intact, undamaged brains by
careful scrutiny of cases involving brain damage
•Lesion: specific area of damage
Studying Split-Brain Patients
•Shown a spoon on the left and a fork on the right, a patient sees the fork, and picks up the
spoon. This is because the left hemisphere controls the right side of the body and vice versa.
Data From Neuroimaging
•Computerized tomography (CT) for brain’s structure
•Passage of x-rays through the head
•X-rays absorbed less by fluid than by brain cells and less by brain cells than bone
•Photographic negative shows brain injury because dead cells contain more water than
healthy living brain cells
•Positron emission tomography for brain’s activity
•Injection of radioactive substances that decay in minutes into the bloodstream and reach
the brain, see what tissues use more of the substance
•Decaying radioactivity gives off photons that are detected by Geiger counters placed
around the head
•Magnetic resonance imaging
•Relies on the magnetic properties of the atoms that make up the brain tissue, and it yields
fabulously detailed pictures of the brain
•Functional magnetic resonance imaging
•Measures the oxygen content in the blood flowing through each region of the brain; this
turns out to be an accurate index of the level of neural activity in that region
•Provides an incredibly precise picture of the brain’s moment-by-moment activities
•The results of CT scans and MRI scan are relatively stable, changing only if the person’s brain
structure changes. The results of PET or fMRI scans, in contrast, are highly variable, because
the results depend on what task is being performed
•One type of communication is between neurons, and another is within neurons
•The “input” part of a neuron is most sensitive to neurotransmitters
•An electrical pulse, made possible by a flow of charged atoms (ions) in and out of the neuron
allows for signals to go from one end of a cell to the other
•Electroencephalography: a recording of voltage changes occurring at the scalp that reflect
activity in the brain underneath. The result of this procedure is an electroencephalogram, or
an EEG.
•Event-related potential: changes in EEG in the brief period just before, during and after the
event
Document Summary
Has less activity when dreaming, which is why dreams are often bizarre. The study of the brain: the brain weighs about 3 to 4 pounds, size of a small melon, contains a trillion nerve cells, ten trillion glial cells. Includes the amygdala and hippocampus; essential for learning and memory; figure 2. 4. Lateralization: commissures: thick bundles of bres that carry information back and forth between the two hemispheres, the largest commissure being the corpus callosum. Studying split-brain patients: shown a spoon on the left and a fork on the right, a patient sees the fork, and picks up the spoon. This is because the left hemisphere controls the right side of the body and vice versa. Do they cause them: the study of brain lesions can help us overcome this correlational data problem, transcranial magnetic stimulation: creating series of strong magnetic pulses at a speci c location on scalp, causing temporary disruption in brain region.
