Neurophysiology of Vocal Learning, Multimodal Processing & Neuromodulation Lab
The Speech and Language Center of the Department of Neurology conducts basic neurophysiological studies in the songbird zebra finch, and functional magnetic resonance imaging (fMRI) and brain magnetic stimulation studies in humans. The songbird research pertains to the neurobiology of vocal learning and animal models of speech-motor disorders. Under projects supported by NIDCD, NIMH and NSF we have made several key observations: During the normal development of birdsong in zebra finches, variant birdsongs exist that contain repetitive vocal patterns resembling dysfluencies of stuttering (figure1); modifying the social environment (e.g., the birds with phonatory iterations are exposed to birds singing normal bird song) produces some recovery toward normal singing patterns.
Figure 1. Normal and variant birdsongs
A. Spectrogram of a normal zebra finch song.
B. Spectrogram of a variant song containing syllable repetitions (R).
C. A male-female zebra finch pair (Helekar, Salgado-Commissariat Rosenfield and Voss (2013).
Our human fMRI studies focus upon brain multimodal, biological motion and mirror neuron processing systems in normal subjects and people who stutter. We are using traditional general linear model-based methods of analysis of fMRI data, and also contributing to the development of functional connectivity and functional spatial mapping methods.
Figure 2. fMRI in birds with variant songs (repeaters) and normal songs (non-repeaters)
Mean BOLD activation for four different auditory stimuli - tutor song (TUT), 2 kHz pure tone (TONE), bird’s own song (BOS) and conspecific song (CON) for 8 non-repeater controls birds (Non-repeaters), and 8 repeater birds (Repeaters). Colors denote correlation coefficients R, individually scaled in each plot, overlaid to averaged EPI images (grey). White border depicts the brain template outline. The main activated area that is consistently activated in all images corresponds to NCM, CM and field L region. Difference images represent the difference in z values between non-repeaters and repeaters. (Helekar, Salgado-Commissariat and Voss, 2010).
Figure 3. Recording of LFP responses to audiovisual call stimuli
A. Picture showing an awake freely moving bird during recording with the wireless headstage and helium balloon attached to its head.
B. A diagram of the zebra finch brain showing labeled structures in which recording electrodes were placed.
C. Traces showing LFPs recorded from the labeled structures (NCM, L, W and E refer to caudal medial nidopallium, field L, visual wulst and entopallium, respectively). V and A on the left indicate durations of the visual and auditory components of the audiovisual stimulus, respectively. AV, A and V on the top point to responses to audiovisual, audio and visual stimuli, respectively.
Figure 4. Plasticity of the visual motion-sensitive areas
Significant BOLD responses (p ≤ 0.05 Family-wise error-corrected t test) associated with 40 second video with no audio stimulation of moving fingers on the piano (V) minus (i.e. greater than) a still frame of fingers on the piano of the same duration (S) contrast (V – S) in trained pianists (n = 17) and untrained control subjects (n = 16). Glass brain and 3D surface representations of activated areas are shown.