Chapter 15: Evolutionary Perspectives

Important Discoveries in Neurobiology

• Natural Selection
• Architecture of the cerebral cortex
• Functional organization of the brain
• Kaas revised
• DNA structure
• Ethology and Neuroethology
• Sociobiology
• Evolutionary Psychology

Assumptions and Aims of Comparative Neuroscience

• Assumptions
• all behavior in all animals is generated by the nervous system
• brains evolve therefore behavior evolves
• we can gain insight just by studying animals
• Aims
• roots: history of brain and behavior
• rules: how did it change?
• relevance: generalizability

The Comparative Approach

Homology: the retention of a structure, behavior or gene from a common ancestor.

Convergent evolution: similar structures with similar functions can arise independently in different lineages

Out group comparison: phylogenetic relationships among animals

Adaptation and the Brain

Our behaviors are adapted to a simpler life. People are better at detecting some thing immoral rather than a simple logical task. Spatial abilities cary according to sex.

Evolutionary Insights into Human Brain Organizations

Many believe that bigger brains are better, but this appears to not be true. Human brains are larger because they need more problem solving capacity.

Chapter 14: Social Cognition

Self Perception and Self Knowledge


Self-referent effect: enhanced memory for information in relation to the self. There are two hypotheses explaining that memory for self is much better.

• the self represents the depth  of processing effect, memory is better as information is processed more deeply.
• processing information about the self is distinct from all other cognitive structures.

we are able to maintain a sense of self even if we have amnesia. R.B. and K.C.s personality judgments are consistent with judgments provided by their family members. But how accurate are our perception of self? We tend to claim more positive traits than negative to describe ourselves. The ventral anterior cingulate cortex was associated with baking positive judgments,

Perception of Other People

Even 4 month old babies show gamma activity in the occipital channels and late gamma activity over the right prefrontal cortex in response to direct eye contact. Premack  and Woodruff came up with the theory of mind, which describes our ability to make inferences about the mental state of others. Our understanding of others starts at a young age. The MPFC and the temporopatietal junction (rTPJ) in the right hemisphere are implicated.

Convergence in the Perception of Self and Others

Simulation theory: theory of mind is based on the ability to put ourselves in the shoes of another person. Empathy is an important trait to have in order to do this. Empathy is purposely putting yourself in another person's shoes in order to understand their thoughts and feelings. Mirror neurons seem to be important for our ability to empathize with others.

Social Knowledge

Utilization behavior is the extreme dependency on prototypical responses for guiding behavior. Patients with damage to the lateral prefrontal lesions used objects in a prototypical manner. Patients with damage to the orbitofrontal would talk about inappropriate topics. Damasio came up with the somatic maker hypothesis, which states that emotional information in the form of physiological arousal is needed o guide decision making. The Iowa Gambling Task is an example of this phenomenon. In this task, there are two piles for the participants to pick from. Normal patients learn to pick from the pile that maximizes winnings, but those with orbitofrontal damage could not learn to do this.

Neuroeconomics

People should make rational decisions: maximize their rewards and minimize their losses. The insula seems to be involved with negative emotions. 

Chapter 13: Cognitive Control

Working Memory


Miller looked at working memory in monkeys, he especially focused on the later PFC. He trained monkeys on a working memory task that required a successive coding of two stimulus attributes: identity and location. A sample stimulus is presented, then there is a 1 second delay then the objects are shown, one of which matches the sample. They must remember the position. He saw that there are three responses:

• "what" cells respond to specific objects, responses sustained over the delay period
• "where" selective to certain locations
• "what-where" cells respond to specific combo of what and where information

Recency Memory

Patients with frontal lobe lesions are impaired in the ability to organize and segregate events in memory. A recency task involving cards with 2 pictures are given to these patients. They are shown the cards and then are asked which object was most recently presented. People with frontal lobe damage did okay at the recognition task but are impaired at the recency task.

Source Memory

Source memory is about the context of the learning. Squire et al  looked at patients with frontal lobe damage. He gave them and normal patients facts to learn. After 6-8 days of retention interval, they were tested. When they answered the questions correctly they were asked where they had learned the information. Patients with frontal lobe damage performed as well as controls on recall but made mistakes on the source task. Glisky et al looked at just healthy patients but he grouped them into high and low functioning frontal lobes. They listened to sentences about common events, half were read by a women the other half were read by a man. They tested item memory by reading them a novel sentence paired with the study sentences. They were asked which one they had heard and who had read it. The two frontal lobe groups did not differ on recall but did differ on source memory.

Prefrontal Cortex

Patients are given a series of pictures containing letters and squares at random location. They must remember the order of the instruction-relevant stimuli.  If they had to remember the location of the squares activation is greater in the parietal and dorsal prefrontal regions. Remembering the letters caused greater activation in the temporal lobe and inferior frontal cortex of the left hemisphere.

• SPS: more activation for spatial
• IFG: ore activation for verbal
• APF: equal
• DLPF: pre activation when remembered backwards

In the n-back tests, patients needed to say which stimulus matched the stimulus n item ago. Activation in the lateral prefrontal cortex increases as the difficulty is increased.

Goal-Oriented Behavior

Wisconsin Card Sorting Task: cards vary along 3 dimensions: shape, color and numerosity. Participants had to sort the cards according to an experimenter-defined sorting rule. The experimenter says whether it is correct or incorrect after each card is played. After the participant has learned the rule, the experimenter will switch the rule again. Patients with frontal lobe lesions have difficulty with this task. They tend to perseverate, which is when they can not learn a new rule, they will apply the initial rule over and over.

Retrieval and Selection of Task Relevant Information

Art Shimamura: PFC can be conceptualized as a dynamic filtering. Focusing on what is important and filter out what is not relevant. Frontal lobes play a critical role in selecting task-relevant information. The stroop task is when colored words spell out color names. Name and colors to don match. Frontal lobe patients tend to have problems with this task.

Anterior Cingulate Gyrus

Operates as an executive attention system. Coordinates activity of others. Highest level of mental processes - it is the direct flow of traffic.

Chapter 12: Attention and Consciousness

Attention involves top-down (voluntary) goal-directed processes and bottom-up (reflexive), stimulus-driven mechanisms. They influence the way information is processed in the brain and can occur early during sensory processing. Balint's syndrome is a visual attention and awareness deficit. Someone who has this syndrome can only perceive one object at a time. 


Theoretical Models of Attention


Attention is defined as the ability to attend to somethings while ignoring others. There are three principle goals:

• To understand how attention enables and influences the detection, perception and encoding of stimulus events as well as the generation of actions based on the stimuli.
• To describe the computational processes and mechanisms that enable these effects.
• To uncover how these mechanisms are implemented in the brain's neuronal circuits and neural systems.

Herman von Helmholt

He did an experiment that looked at covert attention. He had participants look at a screen with letters different distances from the center. The screen was so large that the the participant could not view the screen in its entirety. Covert attention is defined as: the location to which the participant directed his/her attention could be different from the location at which he/she was looking. The participant could see the letters that were in his focus of attention better than those that were not.

E.C. Cherry

He looked at the cocktail effect, which is the idea that in a noisy environment people cal focus on a single conversation. The loudest inputs are not always the best and are not always the ones that everyone focuses on. The goal of the listener is to ignore the louder inputs, this is known as selective auditory attention. However, if the person you are talking to is boring you can attend to another conversation but still stare at the person who is talking to you. He observed the idea of dichotic listening: having two different inputs in each ear, but only attending one of those inputs. They are not able to repeat what was played in the unattended ear. However, you are able to pick up important information in an unattended ear, such as hearing your name.

Donald Broadbent

He came up with the model of selective attention, which states that there is a gating mechanism that determines what information is passed on for higher analysis. But, our mental capacity is limited so we filter our what we want and what we don't know, but some things that we don't want still get through.

Michael Posner

He came up with the spatial cuing paradigm. He carried out an experiment using cued stimuli. Participants are asked to stare at the cross in the center of the computer screen. A cue indicates where the subject should covertly attend. Then the target follows and it is either correctly or incorrectly cued. Posner found that the participants respond faster when it is correctly cued than when it is not.

Reflexive Attention

reflexive cuing: attention to an external stimuli. You will respond to the cue within 50-200 ms. He observed the phenomenon called inhibition of return, which states that you respond more slowly to target that have more space between them and the cues.

Anne Tresiman

She did an experiment that focused on the visual search paradigm. This is the idea that if something sticks out no attention is needed to find it. However, if there are more things that are alike it, it will take longer to find it; this is called conjunction search. 

Attention to Features and Objects.

If cued to expect the target is moving, will we be able to discriminate the target more readily than if it is unexpectedly not moving? Marissa Carrasco looked at this idea. There was a warning tone which was followed by one of three cues: target will not move, an arrow indicating which way it will move and a double-headed arrow indicating it will move left or right. She found that at the cue is not helpful at 150 ms, at 300 ms it helps for spatial but not feature. At 500 ms it helps for both.

Neurophysiology

Raul Hernandez-Peon predicted that: the olivocochlear bundle might exert top-down control over subcortical auditory regions that project to the cortex in the service of early attentional gating of auditory inputs. He found that the activity increases in the cochlear nucleus when the animals attended to the sounds rather than when they ignored the sounds while visually attending to the mice. So, attention to something else diminishes attention to other stimulus.

Steven Hillyard looked and auditory selective attention. He asked participants to attend to sounds in the left or right ear. The auditory sensory ERPs were increased in amplitude when stimuli were attended to compared with when they were ignored. He discovered the P20-50 effect: positive polarity latency between 20-50 ms suggests an early stage of processing. He localized the M20-50 effect to the auditory cortex in the Heschel's gyri.

It is hard to compare the auditory and visual systems because the timing is very different. In the voluntary visual attention, there are changes in the visual ERPs, which begin as early as 70-90 ms after the cue. This is known as the occipital P1, when a visual stimulus appears at a location to which a subject is attending, the P1 is larger in amplitude than when the same stimulus appears at the same location but attention is focused elsewhere.

How are feature and spatial attention related? Spatial attention produces the shortest latency ERP (N2pc). Wanted to see if features were selected before spatial attention was focused on target location. They saw that 140 ms after the onset, the feature ERP was generated in the ventral occipitotemporal cortex. 30 ms after that an N2pc response was generated in more anterior regions. This study indicated that the subjects were focusing spatial attention on the target. Feature selective attention precedes visuospatial attention when the location of the target is unknown in advance.

Neuroimaging

Spatial attention leads to activation in the extra striate cortex in the hemisphere opposite to the attended side (attention on the left enhances the right side, and vice versa). Spatial attention influences the processing of visual inputs. Kastner et al saw that in the absence of focused spatial attention, when stimuli are presented simultaneously, they can interfere with one another.

Corbetta et al saw that there are changes in the extra striate cortex when people attend to stimulus features. Selective attention to color, shape etc activate distinct regions of the extra striate cortex.

Attention to objects has been studied by John Duncan. Object properties are a collection of properties that make a person/object identifiable. Duncan compared attention to location to attention to objects. He found that two perceptual judgements about the same object can be made accurately, however they cannot be made accurately about two different objects. Uncued locations that were located on the same object showed an increased activity in the V1, V2, V3 and V4, but there was no activity in these areas when the uncued location was on different ojects.

Animal Studies

Moran and Desimone: they trained animals to attended to one stimulus and ignore another. They recorded responses in the V4. There is a stronger response in the V4 when the stimulus was attended as opposed to not. 

Brad Motter: activity in the V1 changes when competing stimuli were presented. Animals were trained to attend or ignore a stimuli. Motter recorded spike activity - when the animal was covertly attending, spikes were greater than when they were ignored. He also found that the amplitude of attention was alrger when competing stimlui were presented in the visual field compared to the target being alone.

McAdams and Reid: They also looked at the V1. They wanted to characterize the properties of the neurons in the V1 and then seeing if it was influenced by spatial attention. They trained monkeys to fixate on a central point and covertly attend to a black and white screen. A noise was presented to detect a small colored pixel. When the monkey saw the color pixel they were suppose to make a rapid eye movement from fixation to the location on the screen of the color. Spatial attention enhanced the responses of the simple cells but did not affect the spatial or temporal organization of their receptive fields.

Neurology and Neuropsychology of Attention

Unilateral spatial neglect is when one whole side of a person's visual world is gone. Typically the damage to the right parietal and frontal cortical areas are implicated, therefore the left visual field is gone. Some experiments have studied those with spatial neglect. They are given a line test and asked to intersect  the horizontal lines on the paper right in the center of the line. They tend to bisect the line more to the right side. You not only have neglect to external stimuli, but it is in your won memory as well.