From sensory plasticity to behaviour

Question 1

introduction

Answer 1

see notes

• Motor and somatosensory cortex close together - interact/have functional links
• Thalamus - gateway for sensory info - interacts with cortex
• Cerebellum - coords diff actions
• Basal ganglia - interconnected in sensory and motor pathway - deep in brain - subcortical area like thalamus - central function - connectivity’s
• Many interactions happening
• Complex cerebral network seems to be involved in sensory-motor integration, inc. sensorimotor cerebral cortex, basal ganglia and cerebellum
• Cortical frontal and parietal areas strongly interconnected and function together for many aspects of action planning
• Starting from sensory parietal areas, primary somatosensory cortex (S1) consists of postcentral gyrus of parietal lobe, which corresponds to Brodmann areas 3a, 3b, 1, 2
• Axons from thalamic neurons receiving somatic sensations terminate in somatotopically corresponding regions of S1
• S1 projects to secondary somatosensory cortex (SII), located on superior border of lateral fissure
• Posterior parietal cortex (PPC) involved in spatial attention, spatial awareness and multisensory integration (Colby and Goldberg, 1999)
• Recent studies suggest that PPC plays imp role in diff action-related functions, inc. movement intention (together with frontal areas; Andersen & Buneo, 2002)
- PPC crucial node for sensory-motor integration, in that it integrates extrinsic (from ‘external’ world) and intrinsic (from body) sensory inputs in order to create cognitive representation of movement for motor planning and understanding

Question 2

Similarities between the song system and mammalian motor behaviour pathways (Nottebohm, 2005)

Answer 2

• HVC projects to nucleus RA directly (PDP), and indirectly via Area X, the dorsolateral anterior thalamic nucleus (DLM), and LMAN (AFP)
• Shares similarities with mammalian pathway cortex –> basal ganglia –> thalamus –> cortex

see notes

Question 3

Similarities between the song system and mammalian motor behaviour pathways (Nottebohm, 2005) research

Answer 3

There is a tradition in biology of using specific animal models to study generalizable basic properties of a system. For example, the giant axon of squid was used for the pioneering work on nerve transmission; the fruit fly (Drosophila) has played a key role in researchers discovering the role of homeobox genes in embryogenesis; the sea slug (Aplysia) is used to study the molecular biology of learning; and the round worm (Caenorhabditis elegans) is used to study programmed cell death. Basic insights gained from these four systems apply widely to other multicellular animals. Here, I will review basic discoveries made by studying birdsong that have helped answer more general questions in vertebrate neuroscience

Question 4

Basal ganglia modulate motor outputs and action selection (Smeets et al., 2000)

Answer 4

• Tetrapod vertebrates share a common pattern of basal ganglia (BG) organisation and connectivity in striato-pallidal systems
• Shared chemical markers: dopamine, substance P and enkephalin
• Further similarities in devel and expression of homeobox (Hox) genes (reg genes that control devel in all multicellular organisms, from fungi-humans)
- Mammals have dramatic increase of projections from cortex (pallium) in processing of thalamic sensory info from diff modalities relayed to BG - role extends beyond motor control to inc also cog, emotional, and sensorimotor functions (via loops that have reciprocal connections with frontal, limbic and sensory systems)

see notes

• Dorsal and ventral striatopallidal systems
• The dorsal and ventral striatopallidal systems.
• The basal ganglia are organised into dorsal and ventral striatopallidal systems in all tetrapods.
• For each vertebrate class, 2 representative transverse sections at a rostral (A) and caudal (B) telencephalic level illustrate the relative position of striatal and pallidal structures.
• Although in the literature different names have been given to homologous structures, the same colours have been used for comparable regions in each tetrapod to simplify identification.
** See paper for abbreviations **

Question 5

Basal ganglia modulate motor outputs and action selection (Smeets et al., 2000) research

Answer 5

Jia et al. (2010)

Question 6

Jia et al. (2010)

Answer 6

The role of electro-acupuncture (EA) stimulation on motor symptoms in Parkinson’s disease (PD) has not been well studied. In a rat hemiparkinsonian model induced by unilateral transection of the medial forebrain bundle (MFB). EA stimulation improved motor impairment in a frequency-dependent manner. Whereas EA stimulation at a low frequency (2 Hz) had no effect, EA stimulation at a high frequency (100 Hz) significantly improved motor coordination. However, neither low nor high EA stimulation could significantly enhance dopamine levels in the striatum. EA stimulation at 100 Hz normalized the MFB lesion-induced increase in midbrain GABA content, but it had no effect on GABA content in the globus pallidus. These results suggest that high-frequency EA stimulation improves motor impairment in MFB-lesioned rats by increasing GABAergic inhibition in the output structure of the basal ganglia.

Question 7

Basal ganglia already appear in the early vertebrates (Stephenson-Jones et al., 2011)

Answer 7

• All of major components of basal ganglia in phylogenetically oldest group of vertebrates, lampreys (jawless fish)
• Exaptation: function changed to perf similar computations for diff info in parallel loops (functional modules) - motor, emotional and cog
• Limbic module: pref for reward (e.g. Lobo et al., 2010)
• Motor module: action selection (e.g. Kravitz et al., 2010)
- Multiply basal ganglia connections

see notes

Question 8

Basal ganglia already appear in the early vertebrates (Stephenson-Jones et al., 2011) research

Answer 8

• Background
○ Although the basal ganglia are thought to play a key role in action selection in mammals, it is unknown whether this mammalian circuitry is present in lower vertebrates asa conserved selection mechanism. We aim here, using lamprey, to elucidate the basal ganglia circuitry in the phylogenetically oldest group of vertebrates (cyclostomes) and determine how this selection architecture evolved to accommodate the increased behavioral repertoires of advanced vertebrates.
• Results
○ We show, using immunohistochemistry, tract tracing, and whole-cell recordings, that all parts of the mammalian basal ganglia (striatum, globus pallidus interna [GPi] and externa [GPe], and subthalamic nucleus [STN]) are present in the lamprey forebrain. In addition, the circuit features, molecular markers, and physiological activity patterns are conserved. Thus, GABAergic striatal neurons expressing substance P project directly to the pallidal output layer, whereas enkephalin-expressing striatal neurons project indirectly via nuclei homologous to the GPe and STN. Moreover, pallidal output neurons tonically inhibit tectum, mesencephalic, and diencephalic motor regions.
• Conclusions
- These results show that the detailed basal ganglia circuitry is present in the phylogenetically oldest vertebrates and has been conserved, most likely as a mechanism for action selection used by all vertebrates, for over 560 million years. Our data also suggest that the mammalian basal ganglia evolved through a process of exaptation, where the ancestral core unit has been co-opted for multiple functions, allowing them to process cognitive, emotional, and motor information in parallel and control a broader range of behaviors.

Question 9

Of flies and men: arthropod central complex homologous to BG? (Strausfeld & Hirth, 2013; Fiore et al., 2015)

Answer 9

• Similarities in action selection circuitries
• Sensorimotor loop responsible for processing multiple sensory stim that are somatotopically (mapped relative to body) organised
- Modulated by dopamine amplifying info and mediating learning

see notes

Question 10

Fiore et al. (2015)

Answer 10

Survival and reproduction entail the selection of adaptive behavioural repertoires. This selection manifests as phylogenetically acquired activities that depend on evolved nervous system circuitries. Lorenz and Tinbergen already postulated that heritable behaviours and their reliable performance are specified by genetically determined programs. Here we compare the functional anatomy of the insect central complex and vertebratebasalgangliato illustrate their role in mediating selection and maintenance of adaptive behaviours. Comparative analyses reveal that central complex andbasalgangliacircuitries share comparable lineage relationships within clusters of functionally integrated neurons. These clusters are specified by genetic mechanisms that link birth time and order to their neuronal identities and functions. Their subsequent connections and associated functions are characterized by similar mechanisms that implement dimensionality reduction and transition through attractor states, whereby spatially organized parallel-projecting loops integrate and convey sensorimotor representations that select and maintain behavioural activity. In both taxa, these neural systems are modulated by dopamine signalling that also mediates memory-like processes. The multiplicity of similarities between central complex andbasalgangliasuggests evolutionarily conserved computational mechanisms for action selection. We speculate that these may have originated from ancestral ground pattern circuitries present in the brain of the last common ancestor of insects and vertebrates.

Question 11

Injection of APV impairs reward-based action learning (Yin et al., 2005)

Answer 11

• 2 learning processes in dorsal striatum
○ Sensorimotor that mediates stim-dependent habitual responses (dorsolateral striatum)
○ Associate required for learning goal-directed actions (dorsomedial striatum)
• Operant conditioning
○ Pretraining: rats trained to perf 2 lever-press actions for common outcome
○ Training: single session during which 2 actions rewarded with unique outcomes (encode unique action-outcome associations); food pellets and fruit punch
○ Test: outcome devaluation test (satiate with reward prior to test), discrim between lever predicting devalued (Dev) and non-devalued (Non) reward
• Infusion of APV (aCSF - artificial cerebral spinal fluid in controls):
- Effective after pretraining
- Not effective after training

see notes

Question 12

Injection of APV impairs reward-based action learning (Yin et al., 2005) research

Answer 12

Although there is consensus that instrumental conditioning depends on the encoding of action–outcome associations, it is not known where this learning process is localized in the brain. Recent research suggests that the posterior dorsomedial striatum (pDMS) may be the critical locus of these associations. We tested this hypothesis by examining the contribution ofN‐methyl‐d‐aspartate receptors (NMDARs) in the pDMS to action–outcome learning. Rats with bilateral cannulae in the pDMS were first trained to perform two actions (left and right lever presses), for sucrose solution. After the pre‐training phase, they were given an infusion of the NMDA antagonist 2‐amino‐5‐phosphonopentanoic acid (APV, 1 mg/mL) or artificial cerebral spinal fluid (ACSF) before a 30‐min session in which pressing one lever delivered food pellets and pressing the other delivered fruit punch. Learning during this session was tested the next day by sating the animals on either the pellets or fruit punch before assessing their performance on the two levers in extinction. The ACSF group selectively reduced responding on the lever that, in training, had earned the now devalued outcome, whereas the APV group did not. Experiment 2 replicated the effect of APV during the critical training session but found no effect of APV given after acquisition and before test. Furthermore, Experiment 3 showed that the effect of APV on instrumental learning was restricted to the pDMS; infusion into the dorsolateral striatum did not prevent learning. These experiments provide the first direct evidence that, in instrumental conditioning, NMDARs in the dorsomedial striatum are involved in encoding action–outcome associations

Question 13

Basal ganglia are involved in motor learning (Doyon & Benali, 2005)

Answer 13

Experience-dependent changes in the brain depend on whether subjects are required to learn a new sequence of movements (motor sequence learning)/learn to adapt to env perturbations (motor adaptation)

see notes

Question 14

Basal ganglia are involved in motor learning (Doyon & Benali, 2005) research

Answer 14

Sato et al. (2020)

Question 15

Sato et al. (2020)

Answer 15

Motor skill learning leads to task-related contextual behavioral changes that are underpinned by neuroplastic cortical reorganization. Short-term training induces environment-related contextual behavioral changes and neuroplastic changes in the primary motor cortex (M1). However, it is unclear whether environment-related contextual behavioral changes persist after long-term training and how cortical plastic changes are involved in behavior. To address these issues, we examined 14 elite competitive swimmers and 14 novices. We hypothesized that the sensorimotor skills of swimmers would be higher in a water environment than those of novices, and the recruitment of corticospinal and intracortical projections would be different between swimmers and novices. We assessed joint angle modulation performance as a behavioral measure and motor cortical excitation and inhibition using transcranial magnetic stimulation (TMS) at rest and during the tasks that were performed before, during, and after water immersion (WI). Motor cortical inhibition was measured with short-interval intracortical inhibition and long-interval intracortical inhibition by a paired-pulse TMS paradigm. We found that 1) the sensorimotor skills of swimmers who underwent long-term training in a water environment were superior and robustly unchanged compared with those of novices with respect to baseline on land, during WI, on land post-WI and 2) intracortical inhibition in water environments was increased in swimmers but was decreased in non-swimmers at rest compared to that on land; however, the latter alterations in intracortical inhibition in water environment were insufficient to account for the superior sensorimotor skills of swimmers. In conclusion, we demonstrate that environment-related contextual behavioral and neural changes occur even with long-term training experience.

Question 16

Sensory mapping can change with perceptual experience and learning (Rasumssen, 1982; Merzenich et al., 1984; Recanzone et al., 1990; Pleger et al., 2003; Gunduz et al., 2020)

Answer 16

• Cortical representations can change with use: owl monkey train for several months at task using fingers 2-4
• Reorganisation of somatosensory cortex maps following:
○ Digit amputations in racoon and monkey
○ Peripheral nerve stim in cats
Passive touching of fingertips in humans (fMRI, primary and second somatosensory cortex)

see notes

Question 17

Sensory mapping can change with perceptual experience and learning (Rasumssen, 1982; Merzenich et al., 1984; Recanzone et al., 1990; Pleger et al., 2003; Gunduz et al., 2020) research

Answer 17

Elbert et al. (1995)

Huxlin et al. (2009)

Orban et al. (2004)

Question 18

Elbert et al. (1995)

Answer 18

see notes

• Areas in somatosensory cortex changed - distance between digit 1-5 in brain map
- And the same thing happens I humans after being trained for specific task

Question 19

Huxlin et al. (2009)

Answer 19

Damage to the adult, primary visual cortex (V1) causes severe visual impairment that was previously thought to be permanent, yet several visual pathways survive V1 damage, mediating residual, often unconscious functions known as “blindsight.” Because some of these pathways normally mediate complex visual motion perception, we asked whether specific training in the blind field could improve not just simple but also complex visual motion discriminations in humans with long-standing V1 damage. Global direction discrimination training was administered to the blind field of five adults with unilateral cortical blindness. Training returned direction integration thresholds to normal at the trained locations. Although retinotopically localized to trained locations, training effects transferred to multiple stimulus and task conditions, improving the detection of luminance increments, contrast sensitivity for drifting gratings, and the extraction of motion signal from noise. Thus, perceptual relearning of complex visual motion processing is possible without an intact V1 but only when specific training is administered in the blind field. These findings indicate a much greater capacity for adult visual plasticity after V1 damage than previously thought. Most likely, basic mechanisms of visual learning must operate quite effectively in extrastriate visual cortex, providing new hope and direction for the development of principled rehabilitation strategies to treat visual deficits resulting from permanent visual cortical damage.

Question 20

Orban et al. (2004)

Answer 20

The advent of functional magnetic resonance imaging (fMRI) in non-human primates has facilitated comparison of the neurobiology of cognitive functions in humans and macaque monkeys, the most intensively studied animal model for higher brain functions. Most of these comparative studies have been performed in the visual system. The early visual areas V1, V2 and V3, as well as the motion area MT are conserved in humans. Beyond these areas, differences between human and monkey functional organization are increasingly evident. At the regional level, the monkey inferotemporal and intraparietal complexes appear to be conserved in humans, but there are profound functional differences in the intraparietal cortex suggesting that not all its constituent areas are homologous. In the long term, fMRI offers opportunities to compare the functional anatomy of a variety of cognitive functions in the two species.

Question 21

Plasticity in sensory and motor systems is reciprocally linked (Ostry & Gribble, 2016)

Answer 21

• Acquisition of motor skills involves both perceptual and motor learning
• Playing tennis - learning to feel a good serve - learned perception
• Learning a language - learning to distinguish its sounds
• Combining passive movement with sensory input (follow direction of movement) improves learning of complex trajectories (Wong et al., 2012)
- Changes in connectivity that strengthens networks in both primary motor cortex (M1) and primary somatosensory cortex (S1)

see notes

Changes in motor and somatosensory cortex even though motor task in principle

Question 22

Plasticity in sensory and motor systems is reciprocally linked (Ostry & Gribble, 2016) research

Answer 22

Lee and Whitt (2015)

Barkan et al. (2017)

Question 23

Lee and Whitt (2015)

Answer 23

Sensory loss leads to widespread adaptation of brain circuits to allow an organism to navigate its environment with its remaining senses, which is broadly referred to as cross-modal plasticity. Such adaptation can be observed even in the primary sensory cortices, and falls into two distinct categories: recruitment of the deprived sensory cortex for processing the remaining senses, which we term ‘cross-modal recruitment’, and experience-dependent refinement of the spared sensory cortices referred to as ‘compensatory plasticity.’ Here we will review recent studies demonstrating that cortical adaptation to sensory loss involves LTP/LTD and homeostatic synaptic plasticity. Cross-modal synaptic plasticity is observed in adults, hence cross-modal sensory deprivation may be an effective way to promote plasticity in adult primary sensory cortices.

Question 24

Barkan et al. (2017)

Answer 24

Studies in Passerines have found that migrating species recruit more new neurons into brain regions that process spatial information, compared with resident species. This was explained by the greater exposure of migrants to spatial information, indicating that this phenomenon enables enhanced navigational abilities. The aim of the current study was to test this hypothesis in another order—the Columbiformes – using two closely-related dove species—the migrant turtle-dove (Streptopelia turtur) and the resident laughing dove (S. senegalensis), during spring, summer, and autumn. Wild birds were caught, treated with BrdU, and sacrificed 5 weeks later. New neurons were recorded in the hyperpallium apicale, hippocampus and nidopallium caudolaterale regions. We found that in doves, unlike passerines, neuronal recruitment was lower in brains of the migratory species compared with the resident one. This might be due to the high sociality of doves, which forage and migrate in flocks, and therefore can rely on communal spatial knowledge that might enable a reduction in individual navigation efforts. This, in turn, might enable reduced levels of neuronal recruitment. Additionally, we found that unlike in passerines, seasonality does not affect neuronal recruitment in doves. This might be due to their non-territorial and explorative behavior, which exposes them to substantial spatial information all year round. Finally, we discuss the differences in neuronal recruitment between Columbiformes and Passeriformes and their possible evolutionary explanations. Our study emphasizes the need to further investigate this phenomenon in other avian orders and in additional species.

Question 25

Vision supplements hearing in owl prey detection (De Bello et al., 2001)

Answer 25

• Auditory map in external nucleus of midbrain aligned with retinotopic visual input and controls head movements (via hindbrain)
• During devel experimental manips targeted auditory input (ear plug) and visual input (prism) - when removed, sound-guided gaze movements displaced (but not visual gaze) - effect strong in owls <3 weeks (critical period)
- During critical period owls can learn better and correct larger misalignments than later

see notes

Question 26

Vision supplements hearing in owl prey detection (De Bello et al., 2001) research

Answer 26

Friedel et al. (2020)

Question 27

Friedel et al. (2020)

Answer 27

Are alternation and co-occurrence of stimuli of different sensory modalities conspicuous? In a novel audio-visual oddball paradigm, the P300 was used as an index of the allocation of attention to investigate stimulus- and task-related interactions between modalities. Specifically, we assessed effects of modality alternation and the salience of conjunct oddball stimuli that were defined by the co-occurrence of both modalities. We presented (a) crossmodal audio-visual oddball sequences, where both oddballs and standards were unimodal, but of a different modality (i.e., visual oddball with auditory standard, or vice versa), and (b) oddball sequences where standards were randomly of either modality while the oddballs were a combination of both modalities (conjunct stimuli). Subjects were instructed to attend to one of the modalities (whether part of a conjunct stimulus or not). In addition, we also tested specific attention to the conjunct stimuli. P300-like responses occurred even when the oddball was of the unattended modality. The pattern of event-related potential (ERP) responses obtained with the two crossmodal oddball sequences switched symmetrically between stimulus modalities when the task modality was switched. Conjunct oddballs elicited no oddball response if only one modality was attended. However, when conjunctness was specifically attended, an oddball response was obtained. Crossmodal oddballs capture sufficient attention even when not attended. Conjunct oddballs, however, are not sufficiently salient to attract attention when the task is unimodal. Even when specifically attended, the processing of conjunctness appears to involve additional steps that delay the oddball response.

Question 28

Development of the visual system in mammals after birth

Answer 28

• Diffs in visual abilities of adults and infants
○ Acuity develops during first year v. fast but continues also during later development (up to age 20) as the eye (and lens) continues growing in size
○ In the first month eye-hand coord already starts developing
○ By week 8, babies more easily focus view
○ By 3 months reaching for objects
○ Crawling (approx. 8 months) develops eye-foot-hand coord further
○ Ny 10 months increased visual generalisation for small features in non-relevant objects and improved human face discrim (relevant objects)
- Have poor resolution when born

see notes

Question 29

Development of the visual system in mammals after birth research

Answer 29

Gilbert and Walsh (2004)

Question 30

Gilbert and Walsh (2004)

Answer 30

The primaryvisual cortexis, of course, for vision – or so you would think. But it seems that, in blind people, the primary visual cortex can take on an important role in language processing. This suggests considerable flexibility in the processes by which subregions of the human brain become specialised for different functions

Question 31

Visual cliff experiment (Gibson & Walk, 1960; Kohler, 1964; Stratton, 1897)

Answer 31

Same sized pattern viewed from diff distances generates disparities that visual system (at level of V1) interps as same texture/object at diff distance

see notes

• Young babies won’t crawl over glass because depth perception already developed by age of 5 months
• Other mammal young’s also don’t walk over
- Dark-reared kittens failed test

see notes

Question 32

Stratton (1897)

Answer 32

Investigated adaptation in an inverted visual field. An eight day experiment was conducted on one S. When lenses inverting the visual field were not worn, the eyes were blind folded. The experience was carefully recorded everyday. Six days of the experiment are reported wherein from a feeling of abnormal position of the body, the S learnt to adjust to movement, localization of touch and sound

Question 33

Visual deprivation causes structural changes in the brain

Answer 33

• Experiments in kitten and monkeys reveal that the development and utilisation of structures in V1 (orientation and ocular dominance columns) depend heavily on sensory experience
- Brain functions compete for space and reorganisation will take place

see notes

• Ocular dominance columns (which is most anthropoid primates are really stripes/bands) in layer IV of primary visual cortex of adult macaque monkey
• Diagram indicates labelling procedure; following transsynaptic transport, pattern of geniculocortical terminations related to eye visible as series of bright stripes in autoradiogram of section through layer IV in plane of cortex (as if looking down on cortical surface)
• Dark areas zones occupied by geniculocortical terminals related to other eye
- Pattern of human ocular dominance column shown (LeVay et al., 1980)

Question 34

Visual deprivation causes structural changes in the brain research

Answer 34

Sharma et al. (2007)

Question 35

Sharma et al. (2007)

Answer 35

A basic finding in developmental neurophysiology is that some areas of the cortex cortical areas will reorganize following a period of stimulus deprivation. In this review, we discuss mainly electroencephalography (EEG) studies of normal and deprivation-induced abnormal development of the central auditory pathways in children and in animal models.We describe age cut-off for sensitive periods for central auditory development in congenitally deaf children who are fitted with a cochlear implant. We speculate on mechanisms of decoupling and reorganization which may underlie the end of the sensitive period. Finally, we describe new magentoencephalography (MEG) evidence of somatosensory cross-modal plasticity following long-term auditory deprivation.

Question 36

Pre-natal brain development, learning and transnatal sensory memories (Coureaud et al., 2002, Schaal et al., 2020)

Answer 36

• Mammalian new-borns fully depended on milk
• Rabbit mothers lactate pups until 28 days after birth then pups find food independently
- Detecting and competing with siblings for access to milk

see notes

Question 37

Coureaud et al. (2002)

Answer 37

This study investigates the role of prenatal odor learning on postnatal adaptive orientation responses in the newborn rabbit. Preference tests revealed that pups are equally attracted to the odors of placentae and colostrum (Experiments 1–4), suggesting that an odor continuity may exist between the fetal and neonatal environments. To test some predictions derived from this hypothesis, we manipulated the odor of the diet of pregnant‐lactating does to control the chemical niches of their perinates. Fetuses exposed in this way to the odor of cumin (C) were selectively attracted as neonates to the odor of pure C (Experiment 6). Prenatal exposure to C also was followed, to a certain extent, by enhanced attraction to C odor in the placenta or colostrum from females which had consumed it (Experiments 5 & 7). Finally, the functional implications of perinatal odor continuity were tested by disrupting it. The odor component of the feto–neonatal transitional environment revealed indeed to affect the ability of certain pups to gain colostrum and milk at the very first sucking opportunities (Experiment 8).

Question 38

Schaal et al. (2020)

Answer 38

The impact of the olfactory sense is regularly apparent across development. The fetus is bathed in amniotic fluid (AF) that conveys the mother’s chemical ecology. Transnatal olfactory continuity between the odours of AF and milk assists in the transition to nursing. At the same time, odours emanating from the mammary areas provoke appetitive responses in newborns. Odours experienced from the mother’s diet during breastfeeding, and from practices such as pre-mastication, may assist in the dietary transition at weaning. In parallel, infants are attracted to and recognize their mother’s odours; later, children are able to recognize other kin and peers based on their odours. Familiar odours, such as those of the mother, regulate the child’s emotions, and scaffold perception and learning through non-olfactory senses. During juvenility and adolescence, individuals become more sensitive to some bodily odours, while the timing of adolescence itself has been speculated to draw from the chemical ecology of the family unit. Odours learnt early in life and within the family niche continue to influence preferences as mate choice becomes relevant. Olfaction thus appears significant in turning on, sustaining and, in cases when mother odour is altered, disturbing adaptive reciprocity between offspring and carer during the multiple transitions of development between birth and adolescence

Question 39

Insect brains change during behavioural development and with sensory experience (Krofczik et al., 2008; Fahrbach and Van Nest, 2016)

Answer 39

• Honeybee queens experiencing higher temp during pupal devel show larger neuropile volumes with age after adult emergence (increase in number of microglomeruli)• Workers reared in field colonies or greenhouse show diffs in calycal bouton volumes with age after adult emergence (increase in number of microglomeruli)
- Immunohistochemistry: synapsins = phosphoproteins located in boutons of presynaptic neurons in mushroom body calyx - synapsin genes expressed in many animal brain neurons - labelling synapsins with antibody and Kenyon cells with fluorescent dye (phalloidine) gives two-coloured images identifying the MGs

see notes

Question 40

Krofczik et al. (2008)

Answer 40

Worker honeybees proceed through a sequence of tasks, passing from hive and guard duties to foraging activities. The underlying neuronal changes accompanying and possibly mediating these behavioral transitions are not well understood. We studied changes in the microglomerular organization of the mushroom bodies, a brain region involved in sensory integration, learning, and memory, during adult maturation. We visualized the MB lips’ microglomerular organization by applying double labeling of presynaptic projection neuron boutons and postsynaptic Kenyon cell spines, which form microglomerular complexes. Their number and density, as well as the bouton volume, were measured using 3D‐based techniques. Our results show that the number of microglomerular complexes and the bouton volumes increased during maturation, independent of environmental conditions. In contrast, manipulations of behavior and sensory experience caused a decrease in the number of microglomerular complexes, but an increase in bouton volume. This may indicate an outgrowth of synaptic connections within the MB lips during honeybee maturation. Moreover, manipulations of behavioral and sensory experience led to adaptive changes, which indicate that the microglomerular organization of the MB lips is not static and determined by maturation, but rather that their organization is plastic, enabling the brain to retain its synaptic efficacy

Question 41

Fahrbach and van Nest (2016)

Answer 41

Development of the mushroom bodies continues after adult eclosion in social insects. Synapsins, phosphoproteins abundant in presynaptic boutons, are not required for development of the nervous system but have as their primary function modulation of synaptic transmission. A monoclonal antibody against a conserved region of Drosophila synapsin labels synaptic structures called microglomeruli in the mushroom bodies of adult social insects, permitting studies of microglomerular volume, density, and number. The results point to multiple forms of brain plasticity in social insects: age-based and experience-based maturation that results in a decrease in density coupled with an increase in volume of individual microglomeruli in simultaneous operation with shorter term changes in density produced by specific life experiences

Question 42

Recruiting new brain areas when one of the sensory systems does not develop (Merabet & Pascual-Leone, 2010)

Answer 42

• Crossmodal recruitment of occipital visual cortex in blind and auditory cortex in deaf been reported

a. Occipital recruitment for tactile processing such as Braille reading, sound localisation and verbal memory
b. Recruitment of auditory and language-related areas for viewing sign language, peripheral visual processing and vibro-tactile stim

see notes

Question 43

Recruiting new brain areas when one of the sensory systems does not develop (Merabet & Pascual-Leone, 2010) research

Answer 43

Chokron et al. (2016)

Dinse (2006)

Augusto-Oliveira et al. (2019)

Question 44

Chokron et al. (2016)

Answer 44

The most common visual defect to follow a lesion of the retrochiasmal pathways ishomonymous hemianopia(HH), whereby, in each eye, patients are blind to the contralesional visual field. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, hemianopic patients can also present implicit residual capacities, now usually referred to collectively asblindsight. It was recently demonstrated that HH patients can also suffer from a subtle deficit in their ipsilesional visual field, calledsightblindness(the reverse case of blindsight). Furthermore, the nature of the visual deficit in the contralesional and ipsilesional visual fields, as well as the pattern of functional reorganization in the occipital lobe of HH patients after stroke, all appear to depend on the lesion side. In addition to their contralesional and ipsilesional visual deficits, and to their residual capacities, HH patients can also experience visual hallucinations in their blind field, the physiopathological mechanisms of which remain poorly understood. Herein we review blindsight in terms of its better-known aspects as well as its less-studied clinical signs such as sightblindness, hemispheric specialization and visual hallucinations. We also discuss the implications of recent experimental findings for rehabilitation of visual field defects in hemianopic patients

Question 45

Dinse (2006)

Answer 45

Aging exerts major reorganization and remodeling at all levels of brain structure and function. Studies in aged animals and in human elderly individuals demonstrate that sensorimotor cortical representational maps undergo significant alterations. Because cortical reorganization is paralleled by a decline in perceptual and behavioral performance, this type of cortical remodeling differs from the plastic reorganization observed during learning processes in young individuals where map changes are associated with a gain in performance. It is now clear thatbrain plasticityis operational into old age; therefore, protocols for interventions such as training, exercising, practicing, and stimulation, which make use ofneuroplasticityprinciples, are effective to ameliorate some forms of cortical and behavioral age-related changes, indicating that aging effects are not irreversible but treatable. However, old individuals cannot be rejuvenated, but restoration of function is possible through the emergence of new processing strategies. This implies that cortical reorganization in the aging brain occurs twice: during aging, and during treatment of age-related changes

Question 46

Augusto-Oliveira et al. (2019)

Answer 46

Adult neurogenesis occurs in many species, from fish to mammals, with an apparent reduction in the number of both neurogenic zones and new neurons inserted into established circuits with increasing brain complexity. Although the absolute number of new neurons is high in some species, the ratio of these cells to those already existing in the circuit is low. Continuous replacement/addition plays a role in spatial navigation (migration) and other cognitive processes in birds and rodents, but none of the literature relates adult neurogenesis to spatial navigation and memory in primates and humans. Some models developed by computational neuroscience attribute a high weight to hippocampal adult neurogenesis in learning and memory processes, with greater relevance to pattern separation. In contrast to theories involving neurogenesis in cognitive processes, absence/rarity of neurogenesis in the hippocampus of primates and adult humans was recently suggested and is under intense debate. Although the learning process is supported by plasticity, the retention of memories requires a certain degree of consolidated circuitry structures, otherwise the consolidation process would be hampered. Here, we compare and discuss hippocampal adult neurogenesis in different species and the inherent paradoxical aspects.

Question 47

Human speech (Neville et al., 1998; Ulman & Pierpoint, 2005; Ocklenburg et al., 2018)

Answer 47

• Producing speech only one element in talking, and accordingly specific language impairment (SLI) in humans either in grammar/non-linguistic processing (involving brain networks for motor skills)
• Some animals can learn to produce human vocalisations (parrots, dogs, starlings) and even to correctly name features and objects in simple discrim tasks (parrot Alex) - gorillas and chimps trained in American Sign Language (ASL) and learned to represent several hundreds of objects and actions with diff symbols and use them in tasks
• Language related to large variations with underlying patterns and increases with learning which is not observed in apes but in young children (using speech/ASL)
- In deaf people signalling involves same areas as language production and additional areas

see notes

Question 48

Ocklenburg et al. (2018)

Answer 48

The left hemispheric advantage inspeechperception is reflected in faster neurophysiological processing. On the basis of postmortem data, it has been suggested that asymmetries in the organization of the intrinsic microcircuitry of the posterior temporal lobe may produce this leftward timing advantage. However, whether this hypothetical structure-function relationship exists in vivo has never been empirically validated. To test this assumption, we used in vivo neurite orientation dispersion and density imaging to quantify microcircuitry in terms of axon and dendrite complexity of the left and right planum temporale in 98 individuals. We found that a higher density of dendrites and axons in the temporalspeecharea is associated with faster neurophysiological processing of auditoryspeech, as reflected by electroencephalography. Our results imply that a higher density and higher number of synaptic contacts in the left posterior temporal lobe increase temporal precision and decrease latency of neurophysiological processes in this brain region.

Question 49

Humans can learn to echolocate with clicks (Thaler et al., 2011)

Answer 49

• Sounds of (their own) clicks and echoes activate calcarine and temporal cortex in both early and late blind echolocation experts
• Findings suggest that areas devoted to vision recruited for echo analysis
• C1 and C2 trained with experts’ sounds and showed high perf in some tasks
- All subjects showed activation in auditory areas

see notes

Question 50

Thaler et al. (2011)

Answer 50

• Background
○ A small number of blind people are adept at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes. Yet the neural architecture underlying this type of aid-free human echolocation has not been investigated. To tackle this question, we recruited echolocation experts, one early- and one late-blind, and measured functional brain activity in each of them while they listened to their own echolocation sounds.
• Results
○ When we compared brain activity for sounds that contained both clicks and the returning echoes with brain activity for control sounds that did not contain the echoes, but were otherwise acoustically matched, we found activity in calcarine cortex in both individuals. Importantly, for the same comparison, we did not observe a difference in activity in auditory cortex. In the early-blind, but not the late-blind participant, we also found that the calcarine activity was greater for echoes reflected from surfaces located in contralateral space. Finally, in both individuals, we found activation in middle temporal and nearby cortical regions when they listened to echoes reflected from moving targets.
• Conclusions
- These findings suggest that processing of click-echoes recruits brain regions typically devoted to vision rather than audition in both early and late blind echolocation experts.

Question 51

Accuracy of echolocation in blind humans (Milne et al., 2014; Thaler et al., 2018)

Answer 51

• Blind and sighted indvs can learn to echolocate
• Human echolocators (N=8, blind) adjusted loudness and no. of clicks for detection of reflectors at various azimuth angles - task: click and report presence/absence of objects (chance level 50%)
- Increasing intensity and no’s of clicks improves signal-to-noise ratio (imp for weak echoes) - perf impairs if head not moved

see notes

Question 52

Milne et al. (2014)

Answer 52

Similar to certain bats and dolphins, some blind humans can use sound echoes to perceive their silent surroundings. By producing an auditory signal (e.g., a tongue click) and listening to the returning echoes, these individuals can obtain information about their environment, such as the size, distance, and density of objects. Past research has also hinted at the possibility that blind individuals may be able to use echolocation to gather information about 2-D surface shape, with definite results pending. Thus, here we investigated people’s ability to use echolocation to identify the 2-D shape (contour) of objects. We also investigated the role played by head movements—that is, exploratory movements of the head while echolocating—because anecdotal evidence suggests that head movements might be beneficial for shape identification. To this end, we compared the performance of six expert echolocators to that of ten blind nonecholocators and ten blindfolded sighted controls in a shape identification task, with and without head movements. We found that the expert echolocators could use echoes to determine the shapes of the objects with exceptional accuracy when they were allowed to make head movements, but that their performance dropped to chance level when they had to remain still. Neither blind nor blindfolded sighted controls performed above chance, regardless of head movements. Our results show not only that experts can use echolocation to successfully identify 2-D shape, but also that head movements made while echolocating are necessary for the correct identification of 2-D shape.

Question 53

Blindsight-type phenomena reveal residual functions when a sensory system is damaged (Stoerig, 1999; De Gelder et al., 2008; Striemer et al., 2008; Ajina et al., 2015; Ajina & Bridge, 2017)

Answer 53

Damage to V1 causes cortical blindness, loss of conscious vision - patients able to perf visually-guided behavs, like grasping/pointing to location of objects, or avoiding obstacles, correctly at level above chance - known as blindsight

see notes

Question 54

Blindsight-type phenomena reveal residual functions when a sensory system is damaged (Stoerig, 1999; De Gelder et al., 2008; Striemer et al., 2008; Ajina et al., 2015; Ajina & Bridge, 2017) research

Answer 54

Tinelli et al. (2013)

Laurent-Vannier et al. (2006)

Question 55

Tinelli et al. (2013)

Answer 55

It has been shown that unconscious visual function can survive lesions to optical radiations and/or primaryvisual cortex(V1), a phenomenon termed “blindsight”. Studies on animal models (cat and monkey) show that the age when the lesion occurs determines the extent of residual visual capacities. Much less is known about the functional and underlying neuronal repercussions of early cortical damage in humans. We measured sensitivity to several visual tasks in four children with congenital unilateralbrain lesionsthat severely affectedoptic radiations, and in another group of three children with similar lesions, acquired in childhood. In two of the congenital patients, we measured blood oxygenation level dependent (BOLD) activity in response to stimulation of each visual field quadrants. Results show clear evidence of residual unconscious processing of position, orientation and motion of visual stimuli displayed in thescotomaof congenitally lesioned children, but not in the children with acquired lesions. The calcarine cortical BOLD responses were abnormally elicited by stimulation of the ipsilateral visual field and in the scotoma region, demonstrating a profound neuronal reorganization. In conclusion, our data suggest that congenital lesions can trigger massive reorganization of the visual system to alleviate functional effects of early brain insults.

Question 56

Laurent-Vannier et al. (2006)

Answer 56

The purpose of the study was to provide normative data for the Teddy Bear Cancellation Test (TBCT) and to evaluate prospectively the frequency of unilateral spatial neglect (USN) in children with acquired brain injury (ABI). In the control group (n=419; 218 males, 201 females; mean age 5y 1mo [SD 1y 4mo]; range 3 to 8y) omissions were rare and decreased with age. A left displacement of the first three teddy bears cancelled was observed with increasing age. This preferential left-to-right cancelling strategy was interpreted as learned under the influence of reading habits. The same test was used prospectively in 41 children with ABI (24 males, 17 females; mean age 5y 5mo [SD 2y]; range 3 to 8y) admitted to a paediatric rehabilitation department specializing in acquired brain lesions. In patients and controls, children under 6 years of age omitted more items than older children. The localization of omissions was skewed significantly to the left in children with right-sided lesions compared with children with left-sided lesions. USN was observed in seven patients with ABI. Left USN was found in three of the 10 patients with right-sided ABI. Right USN was present in two of the patients with 15 left-sided ABI and two of the 16 patients with non-lateralized ABI. Left USN is frequent in children after right-sided brain injury. The relatively high incidence of right spatial neglect in children is discussed in relation to the development of hemispheric specialization.

Question 57

Subconscious vision and emotions (Tamietto & De Gelder, 2011)

Answer 57

• SC-mediated pathways interconnected with amygdala
• Rapid processing of emotional info, in particular salient stim, such as faces and snakes
• Shirt-cut to drive motor actions, such as fast orienting eye movements
- Many emotional signals are processed without being consciously perceived.

see notes

Question 58

Subconscious vision and emotions (Tamietto & De Gelder, 2011) research

Answer 58

Spering and Carrasco (2015)

Question 59

Tamietto and De Gelder (2011)

Answer 59

• Non-conscious perception of emotional stimuli is present in both healthy observers, as a consequence of experimental manipulation, and in neurological conditions resulting from focal brain damage, such as hemispatial neglect and cortical blindness.
• An emotional stimulus can be perceived non-consciously because it falls outside the focus of attention (a phenomenon referred to as attentional unawareness) or because its sensory analysis is hampered (a phenomenon referred to as sensory unawareness). Although both phenomena render the observer unaware of the stimulus, they involve different neural processes.
• Non-conscious perception of emotional stimuli involves a neural system that is composed of subcortical structures, such as the superior colliculus, the visual pulvinar and the amygdala. This neural system receives visual information directly from the retina — thus bypassing the visual cortex — and has an old evolutionary origin, being present in other species like birds, rats and monkeys.
• The function of this subcortical system is to provide a rapid, but coarse, analysis of the visual stimuli in order to provide reflex-like responses to emotional signals in the environment. Neurophysiological changes and expressive reactions associated with non-conscious perception of emotional stimuli are consistently more rapid and more intense than responses associated with conscious perception of the same stimuli.
- The subcortical system for emotion processing influences cortical activity in several direct and indirect ways. The extent of this cortico–subcortical integration is a crucial factor in affecting visual awareness

Question 60

Spering and Carrasco (2015)

Answer 60

Visual perception and eye movements are considered to be tightly linked. Diverse fields, ranging from developmental psychology to computer science, utilize eye tracking to measure visual perception. However, this prevailing view has been challenged by recent behavioral studies. Here, we review converging evidence revealing dissociations between the contents of perceptual awareness and different types of eye movement. Such dissociations reveal situations in which eye movements are sensitive to particular visual features that fail to modulate perceptual reports. We also discuss neurophysiological, neuroimaging, and clinical studies supporting the role of subcortical pathways for visual processing without awareness. Our review links awareness to perceptual-eye movement dissociations and furthers our understanding of the brain pathways underlying vision and movement with and without awareness.